THE WEATHER ISSUED BY TRAINING DIVISION OF THE BUREAU OF AERONAUTICS U. S. NAVY July 1943 PREFACE This book is intended as a text and workbook to serve avia- tion cadets who have completed an introductory course in aerology and entered the second phase of their training. It presupposes an elementary understanding of the nature and behavior of the atmos- phere in its relationships to flying. Briefly reviewing the character- istics of air masses and fronts, and the conditions under which weather hazards to flight are encountered, it places emphasis on acquainting the cadets with specific, actual weather situations and flight planning problems. Flying conditions in air mass and frontal weather are presented by use of weather maps, weather reports, and pictorial cross sections correlated with maps and based upon surface and radiosonde obser- vations and pilot’s reports. Familiarity with sources of weather information for pilots is increased by report decoding, map com- pletion, and forecast reading exercises. Directions are included for observation and interpretation of the current weather in its relation to flying. Flight planning problems are set to actual weather situations. J. H. CASSADY, Captain, U. S. N., Director of Aviation Training, Bureau of Aeronautics, US. Navy. July 1943. 84”? {3 TL 5’56: Una CONTENTS Page Preface ________________________________________________________ iii UNIT 1.~—A Pilot’s Weather Observations __________________________ 3 UNIT 2.———Air Mass Weather _____________________________________ 12 UNIT 3,—Cold Front Weather ___________________________________ 18 UNIT 4.——VVarm Front Weather __________________________________ 24 UNIT 5.—-The Movement of Weather _____________________________ 28 UNIT 6,—First Principles of Flight Planning _______________________ 42 UNIT 7.—Flight Planning Based on Wind Aloft- _ _ _ _ _ __ _____________ 48 UNIT 8,-Flight Planning for Fog and Low Ceiling Weather _________ 50 UNIT 9,—Flight Planning for Thunderstorm Weather _______________ 56 UNIT 10,—Flight Planning with Icing Conditions ____________________ 64 l UNIT 1 A PILOT’S WEATHER OBSERVATIONS Every day, flying or grounded, a pilot watches the weather. Dur— ing introductory training in Aerology for Pilots you acquired the habit of observing weather with the judgment of a developing pilot—reading meaning (for pilots) in wind, cloud, and pressure changes, and in characteristics of the air masses. Your weather observation and interpretation will continue throughout your flying career. During this training period it is well to keep a record of your daily weather observations—for two reasons: (1) by making and study— ing your record sheet you will learn the usual weather sequences; and (2) by recording of weather in station model form and, later in the course, in sequence report form you gain a lasting familiarity with this (otherwise mysterious) weather “shorthand.” You will read sequence reports and station models as long as you fly! Figure 1A presents the type of station model used on weather maps of the United States Navy—and shows how to read it. It is June off/{oh Cloud.- None V/s/b/e. Toto/Amount ofC/ouds: Overcast ( Tpe and Direction of Movement W/m/ Direction and lea/y.- _ '1 50/77 WNW, Beaufort .3. \ l‘ Emperofure: 40 0/.— \ Present Weather: “*4 O . Lr'q/lr Steady Drizzle. \ \9‘ 9 VIS/b/l/gl-‘55m/I -.- 25 Dew Point: 39 ‘7? a. 5 9 Cell/0960029. ‘ 7);» of lower C/oud: 5frofus. _- yof M/dd/e C/oud: Wife/r A/ro—sfrafus or IVI'mbo—sfro/us, moving from the West _. I F Pressure: /0026 mb. 0 2 6 /* Barometer Endency: Rose /.2mb. d ' + 12/ Last lhree Hollis? 975/ Weather: Rain within Last Six Hours ”U— .077/7. during Last Six Hours. FIGURE 1A.—Explanation of the Navy weather map station model. UNIT l—A PILOT’S WEATHER OBSERVATIONS no stranger to you. Pages 7 to 10 of this workbook contain blanks on which you can enter your daily weather observations. During the first part of the course use the form shown in figure 1A (later we will thoroughly master sequence reports). Pages 7 to 10 provide sufficient blanks for 8 weeks. Each day, at a regular morning hour determined by the instructor, you should make visual observations. One cadet will be assigned each day to make the instrument obser- vations—at the same hour—for the entire class. 0n the record blank (p. 7‘) enter the daily station model and the date and hour of obser- vation, and classify the weather (at time of observation) as “contact,” “instrument,” or “closed,” (see fig. 6A, p. 42). Observe the weather conditions during the day. Then, in the evening, under “notes,” briefly record weather conditions observed during the day—especially those encountered in flight (when you do not fly, record any weather reasons for not flying). Notice and record all frontal approaches and passages, and attempt to identify air masses present. Figures 1B and 1E, containing most of the symbols used on wea— ther map station models, are included in this workbook for ready reference. A PILOT’S VISUAL OBSERVATIONS Pilots learn to make visual weather observations with the expert touch of men who live with the weather. Pilots’ visual observations include: (1) Wind—direction and velocity. (2) Clouds—amount, types, and direction of movement. (3) Ceiling. (4) Visibility. (5) Present weather (and past weather). Though aerologists use instruments for making some of these obser- vations (such as ceiling and wind velocity), pilots rely on the eye. Wind——Direction and Velocity Smoke, flags, wind socks, wind vanes, etc., provide visual evidence of wind direction. When flying, drift provides evidence of wind direction. BEAUFORT SCALE (With adaptations) Terms Probable Bffiiib Seaman’s description “sea by Velocity Velocity, . . . . l d E t' t' l iti e htipelitn f Description of num- Map symbol of wind Wltiatsh'er m.p.h. knots Estimating velocities on an s ima mg ve oc es on s a wdges {)n sea b" Bureau feet 0 9 Calm .................. Calm _______ Less than 1. . Less than 1. . Smoke rises vertically _____________ Sea like a mirror. . . . .............. . ................... Calm (glassy). l \_o Light air.._ ............. Light _______ 1-3 __________ 1—3 __________ Smoke drifts; wind vanes un- Ripples with the appearance of scales are lé ....... Rippled. moved. formed but without foam crests. 2 \__° Light breeze _________________________ 4—7 __________ 4—6 __________ Wind felt on face; leaves rustle; Small wavelets, still short but more pro- 1 ________ Smooth. ordinary vane moved by wind. nounced; crests have a glassy appearance and do not break. 3 \_° Gentle breeze .......... Gentle ______ 8—12 ......... 7—10 _________ Leaves and smalltwigs in constant Large wavelets. Crests begin to break. 2% ______ motion; wind extends light flag. Foam of glassy appearance. Perhaps scat- tered white caps. 4 Lo Moderate breeze ....... Moderate... 13—18 ........ 11-16 ........ Raises dust and loose paper; small Small waves. becoming longer; fairly fre- 5 ________ Slight. branches are moved. quent white caps. 5 Lo Fresh breeze ........... Fresh ....... 19—24 ________ 17—21 ........ Small trees in leaf begin to sway; Moderate waves. taking a more pronounced 10. ...... Moderate. . crested wavelets form on inland long form; many ,white caps are formed. water. (Chance of some spray.) 6 L Strong breeze .......... Strong ______ 25—31 ________ 22—27 ________ Large branches in motion; whis- Large waves begin to form: the white foam )5 ....... Rough. tling heard in telegraph wires; crests are more extensive everywhere. ’ umbrellas used with difficulty. (Probably some spray.) 7 “Lo Moderate gale ........................ 32—38 ________ 28—33 ........ Whole trees in motion; inconveni- Sea heaps up and white foam from break- 20 ....... Very rough. ’ ence felt in walking against the ing waves begins to be blown in streaks ‘ wind. along the direction of the wind. 8 “—0 Fresh gale .............. Gale ........ 39-46 ........ 34—40 ........ Breaks twigs ofi trees; generally Moderately high waves of greater length: 25'. ...... High. impedes progress. edges of crests break into Spindrift. The , foam is blown in well-marked streaks along the direction of the wind. 9 “L0 Strong gale ___________________________ 47—54 ........ 41—47 ........ Slight structural damage occurs.__ High waves. Dense streaks of foam along 30 ....... the direction of the wind. Sea begins to roll. Spray may affect visibility. 10 “-0 Whole gale ............. Whole gale. 55—63 ........ 48-55 ........ Trees uprooted; considerable Very high waves with long, overhanging 35 _______ Very high. structural damage occurs. crests. The resulting foam. in great patches, is blown in dense white streaks along the direction of the wind. 0n the whole, the surface of the sea takes a white appearance. The rolling of the sea be- . comes heavy and shocklike. Visibility is affected. 11 “Lo Storm ................................ 64—75 ........ 56—65 ........ Exceptionally high waves. (Small and 40 ....... medium-sized ships might for a long time be lost to view behind the waves.) The sea is completely covered with long white patches of foam lying along the direction of the wind. Everywhere edges of the wave crests are blown into froth. Visibility affected. 12 “-0 Hurricane .............. Hurricane... Above 75.... Above 65.... The air is filled with foam and spray. Sea 45 or Phenomenal. completely white with driving spray; visi- more. bility very seriome affected. FIGURE 1B. 4 . FLYING THE WEATHER Wind velocity, which aerologists gauge accurately with an ane- mometer, can be estimated by use of the Beaufort system and re- ported in terms of the Beaufort scale (fig. 1B). Figure 1A shows how wind direction and velocity are recorded on the station model. Clouds—Amount, Type, and Direction of Movement Total amount of sky covered with clouds can be estimated to approxi- mately the nearest tenth. Figures 1A and 1E show how amount of clouds is recorded on the station model. Observation of cloud types requires the acquaintance with clouds that can be acquired only through watching clouds and studying pictures and discussions of cloud types. Figures 1A and 1E show how cloud types are recorded on station models. Direction of cloud movements is significant to pilots. It is recorded on station models by an arrow near a cloud symbol, as shown on Relative Humidity and Dew Point [All figures in degrees Fahrenheit] Relative humidity in italics—dew point in bold face. , Air Temperature diflerence between wet bulb and dry bulb temp- m‘“ 1 2 9 4 5 5 7 8 9 1o 11 12 15 14 15 15 67 55 ° ------ {—7 ~20 75 46 2o 5 ------ {—1 -9 —24 78 56 54 15 1° ----- {—5 —2 —1o —27 82 64 46 29 1” ----- 11 5 o —9 85 7o 55 46 3° ----- { 15 12 8 2 —7 —21 87 74 62 49 57 25 15 1 ’5 ----- {22 19 15 1o 5 -5 —15 —-51 30 {89 78 67 56 46 56 26 16 6 ----- 27 25 21 18 14 9 2 -7 —25 35 {91 81 72 65 54 45 56 27 19 10 ----- 99 so 28 25 21 17 15 7 o —11 4o 92 85 75 68 60 52 45 57 29 22 15 7 ----- 58 55 55 so 28 25 21 19 15 7 —1 —14 ‘5 {95 78 71 64 57 51 g 58 51 25 18 12 6 ----- 49 41 98 95 54 91 28 22 18 15 7 -1 —14 5o {95 87 89 74 67 61 55 49 45 58 52 21 16 1o 5 ----- 48 45 44 42 4o 57 94 52 29 25 22 19 15 8 o -15 55 {94 88 82 76 7o 65 59 54 49 45 59 55 28 25 19 14 ----- 59 51 50 49 45 45 41 58 95 55 5o 27 24 20 15 9 50 {94 89 85 78 75 68 65 58 55 48 45 59 54 50 26 21 ----- 59 57 55 59 51 49 47 45 45 4o ‘38 55 92 29 25 21 55 {95 90 85 89 75 7o 66 61 56 52 48 4g 59 55 51 27 ----- 52 52 so 59 57 55 55 51 49 47 45 4o 57 34 91 7° 95 90 86 81 77 72 68 64 59 55 51 48 4o 56 55 ----- 59 57 55 54 52 51 59 57 55 55 51 49 4 44 42 59 ,5 {96 91 95 82 78 74 7o 66 62 58 54 51 47 44 4o 57 ----- 74 72 71 59 58 55 54 59 51 59 57 55 54 51 49 47 so { 91 87 85 79 75 72 68 64 61 57 54 5o 47 44 41 ----- 79 77 75 74 79 72 7o 59 57 55 5s 52 5o 59 55 54 85 {96 92 88 4 89 76 75 7o 66 62 69 56 52 5o 46 44 ----- 94 82 81 so 78 77 75 74 72 71 59 58 55 54 1 ,0 {96 92 89 85 81 78 74 71 68 65 61 58 55 52 49 ‘7 ----- 89 87 95 95 99 82 81 79 78 75 75 78 72 7o 59 7 95 {96 95 99 86 82 79 76 72 69 66 65 60 59 54 52 5o ----- 94 99 91 so 89 87 85 95 99 82 so 79 78 75 74 79 100 {96 95 59 86 85 80 77 75 7o 68 65 62 59 56 a 51 ' -- 99 98 95 95 94 95 91 9o 99 97 85 95 95 82 79 FIGUBI 10. figure 1A. It is shown for one cloud level only. When possible, the direction of movement of middle cloud is indicated. With middle cloud missing and high cloud visible, it is indicated for high cloud. With both middle and high cloud absent or obscured and with low cloud present, station models show the direction of movement of the low cloud. Ceiling A ceiling exists when clouds below 10,000 feet obscure more than one-half of the entire sky. Ceiling is the lowest height at which this condition exists. Ceiling unlimited means no ceiling below 10,000 feet. Ceiling zero means that an overcast (or more than one-half cloud cover) is 50 feet or less above the surface; or ceiling zero can mean that dense fog or heavy precipitation hides the sky from view. Pilots learn to estimate the ceiling by observation from the ground. Aerologists, also, frequently estimate ceiling but may make their observations with ceiling balloons or, at night, with ceiling light projectors.l If possible, cadets in training should have an opportunity to check their ceiling estimates against instrument findings. Practice and study of cloud forms usually result in fairly accurate ceiling esti- mates. Ceiling is entered on the station model in hundreds of feet (30 means 3,000 feet; 08 means 800 feet; etc.). Ceiling zero is entered as 0. When ceiling is unlimited, no ceiling figure is entered on the station model (though some Navy aerologists enter the letter “u”). Visibility In daylight, visibility is the greatest horizontal distance at which the normal eye can see and identify prominent objects—such as mountains, towers, buildings, etc. (At night, aerologists observe lights of specified moderate candlepower at various distances.) On station models, visibility is recorded in miles and tenths of miles (1.7, for example, represents a horizontal visibility of 1.7 miles). On most of the weather maps used in this course, no entry is made when visibility is 10 miles or more. Ceiling and visibility are the chief weather factors determining what flight rules you must follow when making cross-country flights. More about that in Unit 6. Present Weather (and Past Weather) By “present weather” the aerologist means such weather phenomena as precipitation, fog, smoke, haze, thunderstorms, and equally weather or signs of storms. These are symbolized on station models as shown in figure 1A, using the symbols presented in figure 1E. To the pilot many of these “present weather” conditions mean low visibility; some, when associated with freezing temperatures, mean 1A new cloud height measuring device has recently been developed which accurately measures ceiling both day and night. icing problems; and some mean turbulence and gustiness. A severe thunderstorm means most major weather hazards “rolled into one.” Aerologists report and record degrees of intensity of precipitation, fog and thunderstorms: A pilot need not be expert at recognizing whether a particular thunderstorm is “mild” or “moderate”—if reports indicate a thunderstorm, of any degree, he’ll attempt to stay out of it. Intensity of precipitation has meaning to a pilot, for heavy pre- cipitation will reduce visibility more than light precipitation, and can cause more serious icing. The following table may be consulted when recording observations of precipitation: Heavy...... . Falls at rate of more than 0.03 inch in 6 minutes. (Your suit gets soaked in 1 minute.) RAIN _________ Moderate. .. Falls at rate of 0.01 to 0.03 inch in 6 minutes. (Your suit gets soaked in 5 minutes.) Light ....... Falls at rate of less than 0.01 inch in 6 minutes. (Your suit gets soaked in 10 minutes.) Heavy ...... Reduces visibility to about 34 mile.‘ szst ______ Moderate. . . Reduces visibility to about 1 mile. Light ....... Reduces visibility to not less than 1% miles. Heavy ...... Reduces visibility to about 15 mile. Snow ........ Moderate. __ Reduces visibility to about 16 mile. Light _______ Reduces visibility to not less than 91 mile. 1 Without presence of fog. Intensity of fog is reported (in sequence reports) as shown in fol- lowing table: Dense fog .......... Visibility less than 15 mile. Thick tog _____ _. Visibility 19 to 915 mile. Moderate tog. __ Visibility M5 to 99 mile. Light tog _________ Visibility 55 mile or more. Ground tog ........ Forms only a shallow layer through which the sky can be observed. Besidesprecipitation and fog, common obstructions to vision include smoke, dust, drifting snow and haze. When an obstruction to vision cannot be identified as anything else (and limits visibility to 6 miles or less) it is reported as haze. Past weather.—When a pilot knows what kind of weather has hit\ a station within the last 6 hours he has a better basis for judging what may happen there next and what may happen at nearby sta- tions. Weather phenomena that occurred within the 6 hours pre- ceding an observation are commonly recorded on station models as shown in figures 1A and 1E. INSTRUMENT OBSERVATIONS Every good pilot keeps an eye cocked to the weather, becoming‘ expert at the visual observations. Instrument weather observations he leaves to the aerologist—‘at least officially. Every day that he MILLIBARS 1013 946 951 954 957 960 963 966 969 972 975 978 901 984 987 990 993 996 999 1002 K105 1009 1011 14 1017 1020 1023 10% 1029 1032 1035 1038 1041 1044 1047 1050 L I I I I I L | J I I I I I I I I I I I I I I I I I I I I I I I I I | I | I I I I I I I I I I I I I I I l I I I I I I l I 280 201 2&2 2&3 26.4 205 28.6 28.7 285 259 290 29.1 29.2 293 294 295 295 29.7 29.5 298 300 30.1 30.2 303 304 30.5 30.6 30.7 308 30.9 31.0 I N C H E S 2992 FIGURE lD.—-Conversion scale: inches to millibars. flies, however, a pilot knows the pressure and the temperature and dew point—he knows them in relation to other parts of the total weather situation; he knows them primarily in relation to weather hazards. During this training period one cadet each day can be selected to make, for the entire class, these significant instrumental readings: (1) Temperature. (2) Dew point. (3) Pressure (and barometer tendency). (4) Amount of precipitation. Temperature Temperature can be measured with any reliable thermometer. Dew Point Dew point can be measured by use of a psychrometer (which will also show temperature). A psychrometer is made of two thermom- eters, mounted together. When a water-soaked gauze wick is placed over the bulb of one of the thermometers and air is passed rapidly over both, only the dry bulb instrument records true air temperature. The wet bulb instrument reads lower (colder) than the dry bulb, owing to evaporation from the wet gauze. (Evaporation is a cooling process.) When air temperature (dry bulb) and temperature difference between dry bulb and wet bulb are known, dew point can be read from the accompanying Relative Humidity and Dew Point table (figure 10).2 Pressure When setting altimeters, the unit of pressure measurement is the it? if: UNIT l—-—A PILOT’S WEATHER OBSERVATIONS inch; for reading weather maps, however, pilots think of pressure in unit-s of mtllibars (figure 1D). Either a mercurial or aneroid barom- eter may be used to measure atmospheric pressure. If the barometer used in observations is scaled to read in inches of pressure, the inches must be converted to millibars for recording on a station model. The pressure item on a station model is recorded in “tens,” “units” and “tenths” of millibars, with the initial 9 or 10 for hundreds omitted (figure 1A). On all weather map station models and isobars, pressure is recorded at its sea level value; that is, the pressure observed at any station is changed to what it would be if the station were at sea level. If the station is at 1,000 feet, for example, this means adding about 1 inch or about 35 millibars to the local (1,000 feet) pressure. Aneroid barom- eters can be (and usually are) set to indicate the approximate sea- level pressure. Mercurial barometers, however, are not so adjusted and their readings must be changed to sea—level values before recording on station models. The United States Weather Bureau publishes in— structions for correcting mercurial barometer readings to sea-level values. The correction to be applied depends upon air density and temperature and, when done precisely, requires the use of elaborate tables. Approximately correct sea-level pressure reading can be obtained, however, by adding 3.5 millibars or 0.1 inch to the station reading for every 100 feet the station stands above sea level. Barometer tendency, or the pressure trend (direction and rate of change at a station) has a significance. When studied in relation to Warm) wick on the wet bulb thermometer must be kept clean—should be changed when it becomes soiled. Distilled water, or rain water. or melted snow filtered to remove dust particles, should be used to moisten the wick. VA? 72? if 5 fronts, it helps indicate the direction and speed of movement of the front. The barometer tendency figure on a station model (see fig. 1A) represents amount of barometer change (net change) during the 3- hour period preceding the time of observation—expressed in tenths of millibars. (—12, for example, means a decrease of 1.2 millibars in the three hours preceding time of observation.) A barometer characteris- tic symbol is added to give additional information about the barometer behavior (fig. 1A and fig. 1E). Amount of Precipitation Amount of precipitation during the 6‘ hours preceding time of obser- vation is recorded on station models in inches as shown in figure 1A. When the amount is only a trace, it is recorded as T. When the amount is 1.00 inch or more the item is underscored, to call attention to unusu- ally heavy precipitation. (During this training course, this item may be roughly estimated.) MEANING OF WEATHER OBSERVATIONS Each element of a weather observation has meaning to the pilot. Specific meaning of a single element, of course, depends upon its combination with other elements and upon preceding conditions-— past weather. The meaning of cirrus clouds, for example, depends upon pressure tendency, wind direction, and whether the cirrus clouds follow clear weather or stormy weather. From your previous study and general understanding of the influence of weather on flying, out- line the general ways in which the elements of a weather observation have meaning to a pilot. As this course proceeds you can probably complete or improve your outline. Start it now! 7% 79$ WHAT THE ELEMENTS IN A WEATHER OBSERVATION (OR REPORT) TELL A PILOT ABOUT FLYING CONDITIONS: WIND— CLOUDS— CEILING— 5247060-43-2 VISIBILITY— PRESENT WEATHER—- TEM PERATURE— DEW POINT— PRESSURE— BAROMETER TEN DENCY— PAST WEATHER AND AMOUNT OF PRECIPITATION (last six hours)— WEATHER FLYING THE WEATHER MAP SYMBOLS PRESENT WEATHER PRECIPITATION TYPES OF CLOUDS HIGH CLOUDS _) __).) D 2 3—. )__C C HMS THIN THICK CIRRUS OF TUFTED CIRRUS, CIRRUS OR CIRRO—STRATUS CIRRo-CUMULUS CLOUDS CIRRUS CIRRUS ANVIL CLOUD INCREASING CIRRO-STRATUS & CIRRUS MIDDLE CLOUDS “'0‘ ALTO-CUMULUS MIDDLE THIN ALTO'gaRATUS ALTO-CUMULU5 IN SMALL ALTO-CUMULUS “mfi‘T’xuws ALTO-CUMULUS CLOUDS ALTO-STRATUS NIMBO—STRATUS PATCHES '” BANDS ALTO-STRATUS 'N TUFTS Low CLOUDS \ ARROW ON ANY CLOUD Q é 5 '0 "u- " " —‘ SYMBOL SHOWS CUMULUS STRATUS D'RECT'ON OF HER SEMEIIS 0R REFER: ATO- TR — CLOUDS WEATHER CUMULUS “‘MBUS CUMULUS DUMOLDS BAD WEATHER O NO CLOUDS CD ONE-TENTH (5 TWO- 0R THREE-TENTHS O FOUR-, FlVE-, OR SIX-TENTHS 0 SEVEN- 0R EIGHT-TENTHS 0 NINE-TENTHS COMPLETELY COVERED ® SKY OBSCURED BAROMETER CHARACTERISTIC SHOWERS STEADY INTERM I TTANT OTHER RAIN SNOW HAIL RAIN SNOW DRIZZLE RAIN SNOW DRIZZLE o 96 A V V V O O * 'X’ 9 9 O * Q A LIGHT LIGHT LIGHT SLEET OR OR OR LIGHT LIGHT LIGHT LIGHT LIGHT LIGHT MODERATE MODERATE MODERATE 0 'X' A . -)(- 9 . * 9 V V V o o * * 9 9 o 96 9 fl FREEZING HEAVY HEAVY HEAVY MODERATE MODERATE MODERATE MODERATE MODERATE MODERATE DR I 22 LE 0 o o * 9 9 O * 9 N V . * , . A 9 “$53,,“ HEAVY HEAVY HEAVY HEAVY HEAVY HEAVY GLAZE FOG 0 .x. INCREASED DECREASED MODERATE SKY IN WITH WITH WITH GROUND LIGHT TO DENSE DISCERNABLE PATCHES #33; #83; RAIN SNOW DRIZZLE THUNDERSTORMS DRIFTING SNOW 7 7 , o 7 -)(~ A I I< If Ié I< I< IZ I“=3‘I_*::> WITH WITH WITH LIGHT HEAVY LIGHT HEAVY MILD MODERATE SEVERE RAIN SNOW HAIL & LOW & LOW a. HIGH & HIGH MISCELLANEOUS HEAVY SIGNS OF SOUALLY SOUALLY THREATENING DISTANT TROPICAL WATERSPOUT' DUST OR DUST WEATHER WEATHER SKY LIGHTNING CYCLONE SEEN SAND STORM DEVILS SMOKE HAZE /\ / f / \/ \ 27., \ I MODIFYING SYMBOLS >§] TO RIGHT OF SYMBOLS: OCCURRED DURING LAST HOUR (X) AROUND SYMBOL: OCCURRED IN SIGHT OF STATION RISING RISING RISING RISING FALLING FALLING FALLING FALLING THEN FALLING THEN STEADY UNSTEADILY STEADILY THEN RISING THEN STEADY UNSTEADILY STEADILY ' * 9 V —-——— I Z 8 C RAIN SNOW DRIZZLE SHOWERS FOG THUNDERSTORM SAND OR DUST CLOUDY OR STORM OVERCAST FIGURE 1E. UNIT l—A PILOT’S WEATHER OBSERVATIONS Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: ________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: _________ 1 Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: ________ .-_ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: FLYING THE WEATHER Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: .......... Hour: .......... C, N or X: __________ Time of flight: __________ Notes: Date: __________ Hour: __________ C, N or X: __________ Time of flight: __________ Notes: Date: .......... Hour: .......... C, N or X: __________ Time of flight: __________ Notes: Date: .......... Hour: __________ C, N or X: __________ Time of flight: __________ Notes: UNIT l—A PILOT’S WEATHER OBSERVATIONS ___________________________________________________________________ Time of flight: _-_-_-____ ___________________________________________________________________ Time of flight: _-_____-_- NOTES: NOTES: ___________________________________________________________________ Time Offlight: ___-______ _______-__-_________--__-_--_________-_____________________________ Time Offlight: __________ NOTES: NOTES: ___________________________________________________________________ Time Offlight: __________ ________________________________-____________-___________-_________ Time Offlight: _______--_ NOTES: NOTES: ________-______-____-_-____-______________' _________________________ Time Offlight: _____________________________________________________________________________ Timeofflight: __________ NOTES: NOTES: ___________________________________________________________________ Time Offlight: __---_____ __-___________-___-_-______-______________--____-_-____________-___ Time offlight: ___-______ NOTES: NOTES: ___________________________________________________________________ Time offlight: ______-___ __________-_-_____-_______--_________________-_--_-__-_____________ Timeofflight: __________ NOTES: NOTES: ___________ .____-____-____________________________-___:____-________ Time of flight: ___--____- _-_-__--_-_______---_--_-______--____________-_____-___-____-____-_ Time of flight: _________- NOTES: NOTES: 10 ' FLYING THE WEATHER ___________________________________________________________________ Time of flight: --_-______ ___________________________________________________________________ Time of flight: _____-.--- NOTES: NOTES: ___________________________________________________________________ Time Offlight: _____-____ ____-_-_________________--_______-_-___________--_______-_-____-___ Time offlight: ___-____-_ NOTES: NOTES: ___________________________________________________________________ Time offlight: __-_-_____ ---_-___-________-_-______________-__-__-__-_-__-______-_____-_____ Time offlight: ________-_ NOTES: NOTES: Timeofflight: _____________________________________________________________________________ Time of flight: __________ NOTES: NOTES: ___________________________________________________________________ Time offlight: --__-_-_-- ____--_-__-_-__--_-__---___-____-_-__-______--________-___-______-_ Time Offlight: -____-____ NOTES: NOTES: ___________________________________________________________________ Time offlight: _----____- _____-_____-__________-_______________-__-_____-_--________________ Time offlight: ____-____- NOTES: ' NOTES: ___________________________________________________________________ Time offlight: __-___--__ _-_--___-__-__-_-_____________-_____-_--___--______________________ Time offlight: ___-______ NOTES: NOTES: ,‘j ll UNIT l—A PILOT ’S WEATHER OBSERVATIONS 130° 125' HO" "5' 130° 105° 100° 95° 90° 85° v 80° 75° 70° ,1 . . 55° 3 NM , f” . EATTLE . f 34“» _ : :‘v \1 45° \ W4 1 3 m“ , E: \2 («£450 _ 4, “Wiv«~v..uw~m r4. , 4 \..,~_ , 4» , g “wwmum‘.w..w.,wnl kw . 3‘; 33" x “3 3 ‘W . , “E“ a , :3 ‘ b WW“ . MORE?» A ‘ 33 ‘ NORTH DAKOTA \ ' th\ [.1 . g ' yr” ‘s ‘ 9 i 4 L1 51.6 ~ I,» I- g“ , § 0 BISMARCK 3 WWI: 41'5“” , 41 “:17" 2 § § 323 . 093‘ 3% ‘~~«~ ~--».m~...,..~....m. mmm . o W 2:: f, / 3 33k » 4y N ‘wv‘ ‘g ENJ/ 5‘0 '~ .5 x o 4 x 90 4 SOUTH DAKOTA 3 .3MINNEAPOL ’6‘ " 'gwhsi',’ ‘ 40°, , \wlscoNs‘“ , a §AL° 37”“ 3.3 40" g 0 RAPID CITY L 71 c 6‘“ I,” f0“;v::(03$ - 1 , WNWMW ,W-M \ w/w ,www "N“ N 33W 33W ”WMWWM’M» 3 3 WWW Demo" 9 3 ELM“, mu" 3:333 0a" . g \f ‘3 WWW” C' \l ““5,th . “‘LP‘ 84 2 NEBRASKA \ IowA éHICAeofi } pr: J? N p :34“ «.4 .CHEYENNE ‘ 2. o 3‘ ,w 5 M05300 3 ”"1 “MA“ :3 ‘4,“ WM ° 33 3 23‘“ “R? “2‘5"“ 3544mm . \:~3W3W3M¢3{ , LLINO‘S 4 . ‘ND‘ANAPOL‘S I," 55" i3 \. w 2 . DENVER 333W““ ' ”w ’“”‘“””"““”‘m ‘2‘ j , 5‘; 426‘“? . I \w ’3 3 ' \< ' 35 {4 4 KANSAS my? 4.; “Laws ou\sV|t:§ ”I v ‘ R o \ N . A 140%?“ :35. , D o 3 K A N s A s iuussouRl 3x ,“ 33W”. WW _ 4» gm- 3 W'CHITA O J g m {a K a N 1' u c K Y . 1‘ ‘24». H , \--._. W i .1 g m , v \ A 4 .. o F “w— m.% Mwm_w_ ¢~(._. 4., 3% . ’ '33 XV‘LL ““0 L ‘ '3‘ < » WM,” ,M 44444 rM' "‘3 .KNO ch “ Q ‘2 .w ’4’“ ‘0 33 g; 3 ° K I. A H o M A 3.“ A”? T E N N 5 5 E E f l 3 333 “MWK . W\LM\“G / y A 44 . I g :3 1‘ 4: ouT“ \\ AN Disc 9510 g . AM Ali: LL 0 o OKLAHOMARITY ’,\VMEMP§W5 : \ c in o L. N A 0 ~ ENIXC {NEW Mexaco 3 ‘ [ARKANSAsi 3» 3 TLARKQ: £510 "7'1 ’ 3» W» ¢ ,4‘3 g L I 1\‘ 44 24 %§ § 3 "”3vx w I,“ h j 3 K . A x A“ " 30° I‘m, [3 i! g 3/ .M‘ 3NH$5I55IPP' 3t ‘ ‘4‘ \M 30° 33333333 3 3 3 O DALLAS :33“ 3333333333333 31 3 G E o R G | A 3 ”\ *flhm 3 U G 33’ “MW .. mange HMO “WWW. J3 _. WCKSB : A LA 3 Am A 4 ’ ,r [3333 3i 3 ONV‘LL T E 3 3 a 44M"W”3’M¢,,Me‘“' M’Q.JACKS x A s * WNW.» ‘ ‘ . K LA LOCATIONAL and PHYSICAL ‘~ ’ ""33“ 3< 4 w ”\A ‘NEW ORLEANS O 3‘ o f” 1> MAP Of The UN'TED STATES SAN |.:‘T°”'° ' o GALVESTON A. 4 TAM? o 25° ”LEGEND M , «25° :54 LEVEL to 2000' (\4 o coapus cnansn w 2000' f0 5000' \ o M‘“ 5000’ f0 70,000, ‘ % SCALE 4. ’ Iqoool + x, W a” was . KEV wesT 120° 115- no“ ' ””1654 400° 95. 9° ' 835° ‘ 83°. “735° FIGURE lF.—A reference map. 12 UNIT 2 AIR MASS WEATHER When for a period of several days air lies sluggishly or moves slowly over a particular region, it acquires some characteristics of the region— the air becomes warm or cold, moist or dry, depending upon the na- ture of the surface beneath it. After air has stagnated over a large area long enough to acquire the characteristics of the surface beneath it, and over the entire region the physical properties of the air (at each level) become more or less uniform, we call this mass of rather uniform air an air mass. Every air mass eventually moves away from its source region- from the region over which it acquired its basic traits, temperature and humidity. Air masses move to the United States from several directions (fig. 2A). They “import” to us types of weather with characteristics of the source regions. AIR MASS WEATHER—SUMMER SEASON The first part of this unit will acquaint you with a type of weather map that appears quite frequently during the summer season—a map ‘ on which air masses (rather than frontal activities between air masses) dominate the summer weather of the entire United States. In this lesson you will complete the drawing of the accompanying map (Map No. l); and you will be guided through a pilot’s interpre- tation of the air mass weather which the map shows—through an interpretation of what the weather means relative to flying. ‘ { Complete the map—The following table gives data for five station models that have been omitted from the map. Enter this informa- tion on the map, in the proper places, in regular station model form. Eureka, Calif. Shvema-n, Springfield, 11]. Roanoke, Va. litiiiigiii' Togal damount of Overcast ........ Clear ________ Sky obscured. . . Overcast ........ Overcast. c on s. Wind direction... Northwest ...... South south- Southwest ........................ South. east Wind velocity- _._. 5 mph ........... 3 mph ........ 7 mph ___________ Calm ........... 5 mph. High clouds ....... None ........... None __________________________ None ........... None. Middle clouds ..... None. _ .._ _._ . None __________________________ None ........... None. Low clouds ........ Stratus .......... None __________________________ Stratocumulus. . Stratus. Present weather... Thick fog in Smoke ....... Thick log in- Thunderstorm Thick log. Sight of sta- creming. in sight of sta- . tion ' tion. Visibility .......... 4 0 mile ...... 0.4 mile ......... 8 mile ........... 0.2 mile. Temperature ...... 60 F ° F ......... 67° F.... _. 70° F .. 70° F. Dew pomt....._.. 42°F _________ 67° F__.. .. . 70° F. Ceiling ............ 1 200' Unlimited- _ . Zero ............ Zero. Pressure ........... 1020. 3 mb.... 1014. 9 mb ....... 1016. 3 mb ....... 1014. 9 mb Bazongeter ten- . Rose 0. 0mb.. Rose 0. 6 mb. . .. Fell 0. 4 nib ..... Rose 0. 4 mb You will remember that the lines drawn on weather maps, connect— ing points of equal air pressure, are called isobars: at intervals of three millibars: 1,008, 1,011, 1,014, 1,017, etc. Isobars are drawn On this map the isobars for the Great Plains and Rocky Mountain region have been omitted. Draw them on the map where they belong. As you know, the pressure on a weather map is always shown as it would be if the elevation were sea level; and average sea level pressure is 1,013 millibars. center that your new isobars may reveal. H, or a low with a large L. Air masses are classified according to (1) their source regions, and (2) whether they are warmer or colder than the surface over which Indicate on this map any high or low pressure Show a high with a large FLYING THE WEATHER ,' .W POLAR MARITIME ’ (MP) ‘\ i ‘ I l \ \ \{Qt’ \ — MOP/CAI. / \moncAL MARITIMf/ MARIJ’IME \‘ (”LTJ/ (MT)\;\ .; ,/”/ “.07:- ,,,,,,,,,,, ’ ¢ -""" W. ‘ 4%- 9 a FIGURE 2A.——Sourccs and directions of movement of air masses that influence North American weather. they move. Map No. 1 contains the following air mass symbols. Write the full name of each: cP cPk mTk mPk Each air mass is cold or warm, dry or moist, depending upon (1) its source region, (2) the regions over which it has moved, and (3) the amount of time spent in transit. Air masses always originate in high pressure areas, where the air has remained stagnant long enough to acquire characteristics of the source region (fig. 2A) . Name the source region of each of the following air masses: cP mT mP Map No. 1 is a flat weather map; that is, the isobars are far apart, showing low (weak) barometric pressure gradients (only slight hori- zontal change in pressure). Notice how this causes low wind velo- cities: In mph, approximately what is the most common Wind velocity throughout the country on this summer day? These weak pressure gradients are characteristic of summer air mass weather. The summer polar continental air (after it has moved over the Great Plains or into the Middle West) commonly has tem— peratures nearly as high as those of the tropical maritime air, because it has picked up the characteristics of the ground over which it has slowly passed. The nation-wide similarity in temperature causes the slight pressure gradients and low wind velocities. This causes most summer air masses to move sluggishly. Flying conditions within summer air masses.—When flying within any air mass, at a uniform altitude, the temperature and moisture content of the air generally changes very slowly and consistently. With the exception of local variations caused by topography and sur- face material, surface weather also remains similar throughout the area covered by the air mass. Within an air mass, flying weather is influenced mainly by (1) thermal convection (causing bumpy air, cumuli-form clouds and thunderstorms), (2) temperature inversions (cauSing smooth air, strati- form clouds and sometimes fog), and (3) wind blowing over mountains (causing-turbulence; and producing cumuli-form clouds and mountain thunderstorms if air is unstable, and strati—form clouds and upslope fogs, if air is stable). . For examples of summer air mass nuisances to flying study Map No. 1: Notice the smoke that reduces visibility at stations over the north-‘ ern Great Plains and on the Wyoming plateaus. What causes this city smoke to hover near the surface? This map is based on obser- vations made at 0130 E. W. T. Night cooling of the earth’s surface caused a surface temperature inversion, and the light breeze is ideal for developing and deepening the inversion. The smoke hovers low in the settling air. If the air were moist, thick fog would form, because any inversion of moist air causes fog, and presence of smoke makes the fog more thick and persistent by providing many nuclei around which moisture can condense. Witness the famous London fogs—and the Pittsburgh “smog.” On Map No. 1 what causes the fog at Springfield and Moline, Ill.? Will the density of this fog and smoke condition in the cP air increase or decrease after the sun rises and earth’s surface becomes heated? Why? _________________________ Name two indications, shown on the map, of thunderstorms in the southern portion of the 0P air mass. (1) .......................... (2) ............................ Will this thunderstorm activity be increased or decreased during daylight hours? ............ i ______ Why? _____________________ In the southern portion of the mTk air mass, notice the lightning sand thunderstorms; and notice the smoke and fogs at the stations farther north. Why, in both the cP and the mT air, are the fog and smoke more common in the North? ......................... Why are the thunderstorms more common in the South? .......... e}; Iii—e— iii—(idea‘s;— magma, Eli—g— ioi‘rns _when air from the warmer ocean blows over cold coastal water (Map No. 1). The coming of daytime may not change this situation. Why? ......... UNIT 2—AIR MASS WEATHER l3 12 mo. 95° - UNITED STATES NAVY- Aagusf 16,1942 - 0230 [WT 6%- ,152 6d 1 \sg-fow tg?:f:..-..-..-.v’ -.........m._- 3 6‘11 wwfig.’ u“ + 68 6 ' ' 2 . .— '~n—3~~-~CEK.?§..-~--v 5247UOJ43<3 MAP NO. 1 14 AIR MASS WEATHER—WINTER SEASON Winter air masses, like those of summer, provide generally uniform flying conditions over large areas. Because of the greater stability of the winter atmosphere, air mass thunderstorms are far less common in Winter than in summer. Air mass fogs, however, develop in both seasons. Before we can analyze the accompanying maps (Maps Nos. 2, 3, and 4), they should be completed. Complete the Maps—The following table gives weather data for a station model omitted from Map No. 2, one omitted from- Map N o. 3, and two station models omitted from Map N o. 4. Enter this information on these maps in regular station model form. On Map No. 4 some isobars have been omitted from an area extend- ing northwest-southeast from Washington to Texas. Draw them on the map at the regular 3—millibar interval. Indicate on the map, with an H or an L, any high— or low-pressure center that is revealed by the isobars you drew. Flying Conditions Within Winter Air Masses. mT air mass—Map N0. 2 shows an area in which you will soon fly—and reveals one of its flying problems. It shows tropical maritime air moving from sea to land along the Gulf and southern Atlantic coasts of the United States. What is the source region of this air mass? ________________ In summer, when mT air frequently moves far north over the conti- nent, it becomes unstable over the hot summer land. This causes air mass thunderstorms (Map N o. 1). Even in winter some thunder- storms can develop in the moist mT air. Commonly, however, the cool winter land chills the lower layers of an invading mT air mass. FLYING THE WEATHER This causes fog. Notice the fog along the Gulf coast on Map No. 2—— from east of Pensacola to south of Corpus Christi ! Is the fog moderate to dense or is it light? __________ Notice that at several stations it is accompanied by drizzle. Notice also that several inland stations report fog or low cloud. Study the station models and explain why inland Texas has no fog: -. ______________________________________ Corpulseghristl, Seattle, Wash. Roclafssgrmgs, Bufl’alo, N. Y. (Map No. 2) (Map No. 3) (Map No. 4) (Map No. 4) Total amount of clouds. - Sky obscured- _ . Sky 0.8 covered ....... Clear ............ Overcast. Wind direction ........... Southeast _______ Northwest ............ Southwest ...... West. Wind velocity ........... 15 mph __________ mh 10 mph .......... 35 mph. High clouds .............. None ............ Middle clouds ____________ one ___________ Low clouds ______________ None ___________ Stratus. Present weather .......... Thick tog, sky dis- __________________ Light showers of ' cernible. snow. Visibility ________________ 0.3 mile _______________ 30 miles _________ 9 miles. Temperature _____________ 65 F 53° F __________________ ° ____________ 34° F. Dew point._ . _ 52° F ________ _. 14° F ____________ 29°F. Ceiling ...... ._. Unlimited... _ Unlimited ...... 4,000 feet. Pressure _________________ 1025.7 mb... __ 1,039.3 mb _______ 1015.9 mb. Barometer tendency ..... Rose 0. 2 mb ..... Rose 0.2 mb ........... Rose 0.6 mb _____ Rose 1.6 mb. Map N o. 2 shows night weather. Will the fogs more probably increase or dissipate after the coming of daylight? __________________ mP air mass—What is the source region of the mP air shown over the Pacific Northwest in Map No. 3? ____________________________ When such air is moving onto the land from the sea, it causes rain or 75' 1011 " * ‘ ’ 57 ”Z :TZQM .. so- . . ~ 25° MAP NO. 2 showers throughout this mountainous area, snow on the higher moun- tains. Map No. 3, however, reveals a rather stagnant mass of mP air over the land—and the map shows night weather. Notice the fog! Being of maritime origin, and not far removed from over the sea, this air carries considerable moisture. At night, when cool land with only light breeze causes surface temperature inversion, fog develops. At those stations (far inland) Where air holds insufficient moisture to produce fog, the settling air causes smoke to hover near the surface. How and why will this fog condition alter after the coming of daylight? _________________________________________________________ eP air mass.—Map No. 4 shows one of those occasions when polar continental air dominates the weather of nearly all of the United States. Among the air masses, the winter cP is perhaps your best friend. It commonly presents no weather hazards. Though summer cP becomes unstable and brews thunderstorms when it extends far to the south, Winter cP remains more stable. Also, though summer cP often produces night fogs owing to surface temperature inversions, fogs are less frequent in the somewhat drier winter cP air. Notice the excellent flying conditions shown on Map No. 4. The area with overcast skies and precipitation over much of the Great Lakes region provides an exception to the excellent flying condi- tions shown on Map No. 4. When surface temperature is near freezing, aircraft icing can occur while flying through the clouds. Remember that the normal vertical temperature gradient is about 3° F. colder for each 1,000 feet increase in elevation. If it were neces- sary for you to fly across this cloud and precipitation region, how would you avoid icing? _________________________________________ 125° 120° "5° 1026- 1023 300 MILES Oct 19, 1942 2330 PM \07'0 MAP NO. 3 UNIT 2—AIR MASS WEATHER ZS 30° 120‘ H 5' 110° 105° 100° 95° 1023 1020 1017 .43 339 30 Her NB 5 Z? +IOF a 3‘ 2% ’1 iii 01111130 511153 NAVY- November I], [.942 " 0230 5W7 scAL: ; , K ; " m: 300 mass E 3' ° ’ 1 115° 110° 105° 100° . 95° A 45’ f 3 35% ”25° 75' MAP NO. 4 l6 WINTER AIR MASSES OF NORTH AMERICA1 cP Most important air mass affecting North American winters is the polar continental (cP). Acquiring coldness, dryness, and stability while over the frozen northlands, it occasionally surges southward, bringing cold waves as far as the Gulf Coast and sometimes sending chill air to join the trade winds. While at the source, cold air masses are stable. (Pilots find little “bumpiness” in stable cP air over the winter tundras and north woods.) When cold air leaves its source regions, moving over warmer surfaces, the lower air warms, and consequently thermal turbulence develops in the lower layers. Because winter cP air is dry, turbulence must develop to great height before clouds will form—consequently, clear skies prevail in the cP winter air, with scattered cumulus clouds in warmer sections and with strato-cumulus clouds (caused by mechanical turbulence) where strong winds move over rough country. Night fog sometimes forms in winter cP, though less frequently than in summer cP. Temperature inversions at night, however, causes smoke to spread—thus reducing visibility even when the air is too dry to form fog. In general, you’ll like the winter cP. Air is usually smooth, ceilings unlimited, and visibility excellent. When the winter cP air mass becomes sufficiently warmed, as it sometimes may by crossing the Great Lakes or invading Dixie, tur- bulence develops in lower layers and cumulus clouds become numerous. Even here, flight at 1,000 feet generally avoids all trouble. On rare occasions cP air moves across the Rockies and Cascades to coasts of Washington and Oregon. 1t brings to the “webfeet” of that coastal region a respite from their customary winter rains. It may provide excellent flying conditions—clear skies and unlimited visibil- ity; with sufficient moisture in the atmosphere, night fogs may form in stagnant valley air (but less frequently than when mP air stagnates over the Pacific Northwest). When winter cP air moves down the California coast, Los Angeles shivers. When cP air moves out across the Gulf of Mexico it develops in- creasing instability by absorbing warmth from the water; so it picks up moisture and forms cumulo-nimbus clouds and showers (fig. 2B). 4* €001 WNW/WW7" WARM OCT/1N FIGURE 2B.—When cP air of winter moves from cool continent to warm ocean. cA Winter air masses originating over the arctic icecap acquire even lower temperatures and greater stability than cP air. When this air from the Arctic moves southward, its great density (caused by ex- treme coldness) enables it to move with force. “Biting” cold weather strikes the Middle West, and goose pimples develop on Florida vaca- lMaterial on this page is reprinted from the Naval Flight Preparatory text, Aerology for Pilota. You will wish to consult this material while doing the exercise on the next page. FLYING THE WEATHER tionists. After the arctic air, in its southward migration, becomes con- siderably modified, it shows no great contrast to CF air and may be labeled as cP on weather maps. mP Maritime polar air originating over the North Pacific dominates winter weather of the west coast. Moving southward along the coast this air warms, absorbing much moisture. Surface temperatures are never freezing, averaging 46° F. at Seattle, 57° F. at San Diego. Thermal turbulence and turbulence over mountains cause rain, with heavy snowfall over higher mountains. Visibility, generally good, can decrease to zero in the frequent showers. Above the clouds, if you can get there (15,000 feet over the higher mountains), air becomes smooth. This mP air from the North Pacific, having thoroughly wetted the west coast, moves east across the Cascade and Sierra Nevada Moun- tains. The windward west sides of these mountains receive heavy rain, but as the air descends leeward slopes it heats adiabatically and so brings little precipitation to the semidesert plateaus of the West. Rising to pass turbulently over the Rockies, it may cool again to its dew point and lose more moisture. Often it finds cold, heavier cP air over the Great Plains east of the Rockies. This it overrides (the light mP stays on top), often not reaching the Middle West surface. When mP air does move down the east slopes of the Rockies it heats adiabatically and blows as warm, dry wind over the plains near the mountains. This is the “chinook wind” that makes Mon- tanans shed their overcoats. You’ll meet no weather hazards if you get a fighting job in a permanent chinook. Continuing eastward, this mP air on the surface of the Middle West and East differs from cP air only in that it is generally warmer. Sometimes cP air that has moved out a short distance over the North Atlantic circles back to America as mP air. It has been warmed slightly by the North Atlantic, but only slightly. The North Atlantic is nobody’s hot bath. Wind that brings this air is the “northeaster” of New England. It “whips up” rapidly and to great velocity. Stratus clouds and misting rain or snow develop. Icing conditions are severe. This makes mean flying, except above the cloud tops—at about 3,000 feet. mT From the Pacific high, located between California and Hawaii, mT air moves in on the California coast. The source area has rela- tively cool surface temperatures for its latitude (57° to 66° F.); so winter mT air from the Pacific is stable and comparatively dry. When this air moves northward over the ocean, or when it moves over winter-cool California land, (1) it remains stable and non- turbulent, (2) stratus and strato-cumulus clouds form with low ceilings and with tops extending to 10,000 feet or more, (3) drizzles fall along mountain ranges, (4) surface visibility becomes poor in the frequent drizzles and fogs, and (5) icing is infrequent because of warm tem- peratures. In a narrow belt along the California-Oregon coast cold waters upwell from deep in the ocean. This makes Santa Monica Beach invigorating to bathers. It also makes fog—which condenses when mT air (or mP air) blows over the cold coastal water (fig. 2C). insomnia/mm: m MRMMWV- mm (mm mm? 6010 CONT/NE/Vf FIGURE 2C.—Fog caused by on-shore wind and cold coastal water. Over warm waters of the Gulf of Mexico and the Sargasso Sea, mT air masses become warm and moist. Good visibility with a few stratus or strato-cumulus clouds characterize these source regions 3 in winter. When this mT air from the Atlantic or Gulf moves north- ward over cool water or cold land surfaces, stability increases and deep ' fog layers may cover the surface over large areas. Along the New England coast, for example, deep fogs may form in tropical air. Visibility will be very low, and drizzle may result (fig. 2D). F06 0/210!” 373147115 WARM OCEAN COLD (WWI/VENT FIGURE 2D.—When mT (Gulf or Atlantic) air of winter moves northward over cold continent. ‘ S Upper air settling over plateaus of the southwest sometimes pro- duces a distinctive air mass. We call it superior (S). Warmed adiabatically, and finding little moisture to absorb from that dry land, it remains dry and clear. SUMMER AIR MASSES OF NORTH AMERICA cP \ The cP air of summer comes from a thawed-out northland. Moving southward more slowly than the cP of winter, it can develop high temperatures before reaching the Middle West. Characteristics in- clude (1) clear skies with scattered cumulus clouds increasing to the southward; (2) daytime ceilings and visibility unlimited; (3) daytime turbulence at low levels but smooth above 10,000 feet; (4) night temperature inversions causing fog where air is sufficiently moist and causing smoke to spread, reducing visibility. ' South of the Great Lakes the summer cP air contains more moisture . than farther west. This can produce early morning fogs at lake shore stations and a few early afternoon thunderstorms to the southward. mP The so-called “subtropical” high of the Pacific moves north in the northern summer to about 40° to 45° north latitude. From there it yields mP air that moves southeastward to the west coast. The lower layers, warming, pick up considerable moisture. This moisture condenses to coastal fog when chilled by the cold upwelling coastal waters which characterize much of the Pacific Coast of the United States (fig. 20). High winds may lift the fog to stratus or strato- cumulus clouds, which may conceal coast range mountaintops. Coastal mists may fall, and San Francisco hides from pilots. Above the coastal clouds (about 3,000 feet) and also east of the coast ranges, flying conditions are excellent. Qver inland desert areas, however, convection causes some turbulence. On the Atlantic coast the “northeaster” of New England maintains its virility through early summer months, for ice still drifts in the sea ofl' Laborador and high pressure develops over this comparatively cold ocean area. A well—developed low off the New England coast brings in the “northeaster.” As in winter, stratus clouds form but with less of the misting rain. The air flows smoothly above the clouds. FLIGHT From your study of Maps No. 1, 2, 3, and 4, and the descriptive material on page 16, outline (or write notes on) cP Winter Summer cA CHARACTERISTICS UNIT 2—AIR MASS WEATHER mT The subtropical high of the Pacific has moved northward for the summer, giving its outflowing air the mP characteristics. Conse- quently, little mT air reaches California coasts in summer. mP air from the northwest maintains the coastal fogs. The subtropical high of the Atlantic is best developed in summer. At the same time there is low pressure over warm continental areas. Therefore, mT air masses from the Atlantic and the Gulf move farthest inland in summer. Middle Westerners who like summer breezes prefer bedrooms with southern exposures. Hot and moist, this summer mT air has great potentialities as a thunderstorm maker. OF AIR the flight characteristics of the different air masses that influence North American weather. You may Wish to add mP (Pacific) Winter Summer mP (Atlantic) MASS 17 Moving over hot land it develops great thermal turbulence and lives up to its potentialities. (fig. 2E). WARM Off/UV WAR/MEI? C’U/W'WE/VT FIGURE 2E.——-When mT (Gulf or Atlantic) air of summer moves northward over warm continent. WEATHER to your notes as this course progresses and you study more weather maps. Use space provided below: mT (Gulf and Atlantic) Winter Summer mT (Pacific) 18 UNIT 3 GOLD FRONT WEATHER Down in the Ozark Mountains of Missouri flows a “fishing stream” called the Current River. In the heat of summertime, the water of Current River becomes too warm to make a good drink. The stream flows smoothly, and generally the fish won’t bite—except where the cold water from Big Spring enters the river. There, where Big Spring’s cold water enters the warm stream, the water seems almost to boil. It is really turbulent—with the warm water and cold water “fighting for position.” ‘(And, boy, do the fish bite there!) Of course, as the warm and cold water fight it out going down stream, the cold water (being heavier) seems to win and commandeer the bottom of the channel—but they end up being throughly mixed, a stream of uniform temperature. Again Current River flows smoothly (and again the fish must be served caviar before they will be served on the table). Air behaves much like this water. When two air masses meet, atmospheric disturbance results. The greater the temperature differences between the meeting air masses the greater the disturbance. Commonly, a cold air mass advancing from its “polar” source meets a warmer air mass moving northward. Frequently, however, air of an advancing air mass (either cold or warm) overtakes air of an air mass that is moving more slowly in the same direction. In any case, the front of an advancing air mass is called a front. (Peculiar name!) Aloft, it may be called a frontal surface (fig. 3A). FIGURE 3A.——Front and frontal surface. The front of an advancing warm air mass is called a warm front, the front of an advancing cold air mass—a cold front. Wherever air masses clash (along either warm front or cold front) the warmer air, being lighter, must ascend over the colder air. If the advancing air mass is colder (and therefore heavier) than the air mass it displaces, its front edge under runs the lightweight warmer air, causing the warmer air to ascend along the front (fig. 3B). This is a cold front. If the advancing air mass is warmer (and therefore lighter) than the air mass it displaces, its front edge over runs the heavyweight colder air (fig. 3C). This is a warm front. In either case, then, the warm air ascends, cooling as it rises. Wherever the rising air cools to its dewpoint temperature, condensation produces clouds; continuing condensation produces precipitation. An air mass distributes rather uniform weather over the area back of its frontal zone, but the front of an advancing air mass brings weather changes. This unit treats behavior of air (weather) along a cold front. Map No. 5 shows a cold front advancing across the Middle West, moving from the Northwest. The kind of weather—and flying FLYING THE WEATHER ms \\ ! \. \\\\ §~\\\ \\\\\\\ \\‘ \\\\\\\\\\\\\\\\\ "What were you going to say about a cold front?” hazards—found along a cold front depends upon characteristics (temperatures and humidity) of the two air masses; Map No. 5 has rather typical cold front weather. It has a type of frontal weather through which you will fly many times. The drawing above Map No. 5 gives a cross section of the cold front~ the Omaha to Chattanooga profile of the weather shown on the map. This cross section is drawn from information obtained not only from ‘\\:\\\\\ \\\\\\\\\\\\\\\\\\\\\\. \ [+19 ADVANCING COLD AIR 4'4"; FIGURE 3B.—Cold front. Am AbVANcmG WARM FIGURE 3C.—Warm front. 1 GOLD AIR surface observations but also from radiosonde reports of . conditions aloft. It will help you visualize the weather shown on Map No. 5— it will make the map more meaningful to you. Aerologists at naval air stations do not prepare such cross sections for pilots—it would take too. much time. When you look at a weather map you must visualize the cross section of the weather along your flight route! Following are the characteristics of a cold front. Look for them on Map No. 5." Think of them as conditions that effect flying—and through which you will fly: (1) A wind shift at the surface—Wind changes direction when a cold front passes over. Aloft, the wind shift may occur along the frontal surface (see cross section). Wind systems near a front are such that if you stand with your back to the wind (in the northern hemisphere) the front is generally to your left and ahead. In other words, if you are in Tennessee, with a front to the northwest, you will head south when taking off into the wind; while your cousin in Iowa will head north when taking off into the wind. What is the general wind direction northwest of the cold front on Map No. 5? ________________________ Southeast of the cold front? ____________________ (2) Temperature and humidity changes—Behind an advancing cold front, temperatures are always colder than in front of it. There may be much mixing of the warm and cold air, producing a broad belt or zone of temperature transition. With fast moving cold fronts, however, temperature may change abruptly. Away from the front, humidity will vary between the two air masses. In the frontal fog and precipitation area, however, dew point (which is the only humidity factor shown on a weather map) may be high oniboth sides of the front. On map N o. 5 what is the amount of temperature drop between southern Minnesota and northern Illinois? ________________ Between northern Illinois and central Indiana? ________________________ Which has air with temperature nearer its dew point, Omaha or Kirksville? _____________ Why? ________________________________ St. Louis or Nashville? __________________ Why? ________________ (3) Clouds and precipitation.—Increasing cirrus, then alto-stratus and probably alto-cumulus clouds, precede the approach of a cold front. If the ascending warm air is unstable and moist, cumulo- nimbus form along the front; if the ascending warm air is stable and sufficiently moist, the alto-stratus lowers and thickens to stratus and nimbo-stratus. Above the frontal surface, clouds may trail off into alto and cirrus forms. (Or, in some cases when unstable warm air ascends over a slow-moving cold front, cumulo—nimbus form above the frontal surface and possibly extending far back of the surface front. See Map No. 24). In the cold air back of the cold front (below the frontal surface) fog may develop—condensed when cold air invades a warm, rain- moistened landscape and mixes with warm moist air. In the advanc- ing cold air mass, such frontal fog commonly lifts to low stratus, thins, disappears. Soon all is clear overhead. Precipitation is usually heaviest in a narrow belt (50 or 100 miles) immediately preceding the cold front. Light showers or drizzle may fall from alto-stratus, or heavy showers (in unstable air) from cumulo- nimbus, ahead of the frontal belt. Drizzle or light snow may fall from low stratus back of the cold front. On Map N o. 5, along what portion of the cold front is the warmer \ air stable? _____________________________________________________ Along what portion of the cold front is the warmer air unstable?\ (4) Pressure tendency changer-This is of importance to a pilot as one of the indications of approach of a front and frontal weather— and because it influences altimeter settings. A distinct “trough” of low pressure commonly accompanies a cold front. Ahead of the advancing front, therefore, pressure drops; behind the front, pressure rises. UNIT 3—COLD FRONT WEATHER l9 _.--.—--—-—-——--__--.=lo°c_--— o ’-—"-’---— ——--——----“ —---—--—--Ioc —--——---—--- ALTO_ TR _ /“' fl,” ALTO-CUMULUS 5,3 ATus I /-’ uu'z‘lz ALTO — STRATUS , 15,000 /.- é a — Islooo o -— -—_—-—-_ _- —--——--—Ioc—--°’ - - - 0C _ ..—-—— — ——_.-_____-__o°c ——v “' ' — ALTO-STRATUS I ’/-/ (t/hlck) \ I -—I0,000 . _ ,/ — Iqooo —-—.——OC ALTO CUMULUS STRATUS .8 <3 SCALE - ‘ (NIMBo— STRATus) Q E uni/z ALTO-SgATUS § \ " \ 4e ‘5: us 62 105 3 2 +12/ 6 . j +0./ 33 ;v- 46 l—xr/ 60 W7 IO 30 OMAHA KIRKSVILLE ST. LOUIS FIGURE 3D.—Cross-section (Nebraska to Tennessee) showing cold front weather, April 7, 1942. 69 2.152 6! I73 ~6\ 6 o —4 504/0 48 3 \ NASHVILLE CHATTANOOGA April? 1942 0230 6W7- . ‘ ‘scnfgs‘ . \Q L ' Q , f 300 Mug? Q] MAP N0. 5 20 FLYING THE WEATHER LOCATING A COLD FRONT ON THE WEATHER MAP A pilot who can locate fronts on a weather map in the same way that an aerologist does it, has an understanding of frontal weather—he is a weatherwise flyer. The location of a front is, in most cases, a rather complicated procedure; many different factors must be considered— ‘most of them are of importance to pilots. Before drawing in fronts on a weather map the aerologist usually consults the preceding weather maps; these give him a picture of the life history of each air mass and front. Because of the simplicity of the frontal situation on the map used for your following exercise, no previous maps are shown here. One good practice followed by some aerologists is to first locate the areas where the lowest pressure is found, for the “lows” are commonly the centers of the frontal formations (fig. 3E). Having found a low- pressure center (from which a cold front and warm front, and possibly an occluded front, may be extending somewhat as shown in figure 3E) the aerologist—which in this case is going to be you—proceeds to locate the fronts, if any. The cold front is usually easier to locate than the warm front. All right, Kelly, we’ll soon get going! Turn your attention to Map No. 6—to the area between the Great Lakes and the Gulf. We will look for each characteristic of a cold front and draw in a line according to each separate characteristic— then see if we can reconcile the lines. The characteristics of a cold front are: (l) A wind shift at the surface. (2) Temperature change. (3) Pressure trough and pressure tendency change. (4) High humidity in the frOntal zone; and a sequence of cloud types; and frontal precipitation. FIGURE 3E.——Lows are commonly the centers of frontal formations. You will notice that the winds of the southeastern part of the country are southerly while over most of the Great Plain states winds are from the north and northwest. Draw the “wind shift line” on the map. Label it “wind shift line.” Notice that temperatures in central Indiana are 64° and 65° F. while Chicago has a temperature of 38° F. Notice that Arkansas has temperatures nearly 20° F. warmer than neighboring Oklahoma. Draw on the map a line between the warm air mass (mTk) and the cold air mass (cPw). Label it temperature change. Remember that, owing to mixing of air along the front, there is actually a narrow belt or zone (rather than an abrupt line) of temperature transition. Notice that in southeastern Missouri, stations report pressure of 1,000.7 millibars, with higher pressure both to the east and to the west. Notice, also, that east of this area the barometer tendency is down- ward—the barometer is dropping, while to the west the barometer is rising. Southeastern Missouri, then, must be in the pressure trough that accompanies a cold front. Draw in a line marking the pressure trough. Label it pressure trough. Over Minnesota, South Dakota, and Nebraska the dew point is much lower than the temperature~air is dry. The same is true of the interior portions of the southeast. Now look at the belt through Kentucky, Indiana, Illinois, and Missouri. ' You will find high humidity—temperature and dew point close together. On this particular map you will notice that as you get south the dew point temperature becomes increasingly important in locating the front. Draw a high humidity line and label it high humidity. High humidity on the surface is caused either by precipitation or by the fogging up of cold air that invades a rain-moistened area and mixes with warm, moist air. Cloud forms and precipitation can help in the locating of the front. When heavy showers and thunderstorms are occurring in a somewhat narrow belt, it usually signifies the passing of a cold front. By now you should have decided exactly where the cold front is. Draw it on your map. This is done with a solid blue line on hand- drawn maps; so if you have a blue pencil, use it for this cold front. Otherwise, show it as on printed maps with the jagged “teeth” pointing in the direction the front is moving—in this case southeastward. Why is it moving southeastward? Draw in all the isobars that have been omitted from the east central portion of the map. Remember that isobars are drawn at 3 millibar intervals, and remember that they kink where they cross fronts. Next, you can shade the precipitation areas or color them green. We will draw the warm front later. *‘fif‘fi? During this course you will study 29 weather maps. Each presents an actual weather situation. Though these maps are printed, the weather maps you will consult at naval air stations are necessarily hand drawn. Using colored pencils or crayons, complete the following key to weather map fronts and precipitation areas: enter on the key the symbols used to show fronts and precipitation areas on hand—drawn maps. KEY to WEATHER MAP FRONTS and PRECIPITATION AREAS On Printed Maps On Hand Drawn Maps WARM FRONT . _-_‘_-_‘_ "“""(xe;az,-ne;”“' mm "W mks/tam" ' m‘°""‘“ W“ W angst/raga»;Readies/ignite.) OCCLUDED FRONT . .............. ( Pup/91 ._ . ) .............. r I”? AREA with PRECIPITATION 7/ """"""""""""""""""" at TIME of OBSERVATION / //// /% {Area Co/ored firee/I) SHOWERS at TIME of OBSERVATION \ \ \ \ (Grave/71m»; acrossS/mwerA/ea) it? 7k 794* NOTES UNIT 3—COLD FRONT WEATHER 21 130' 125° 120° 115° 110° 105° 100° 95° 90¢ 55° soc 75° 70° 55° 459 40' _ “11:5. 21-. ‘ fig 39 1123,5169? zSILQth-o $33 1.30 'M 35' o 69",, ““m , /‘§;§\gb ‘\°\1 / ‘, V so. / 30° 19¢ « ° UNITED STATES NAVY' 25' Apr/7 I7, 7940 -' 7330 EST 25° \ SCALE 798 Us“ 300 M’LES 110° 115‘I 110° 105° 100° :32 ‘ 0 § 90 85° 30° 75. 524788 0 - 43 4 4 MAP NO. 6 Ion , scale V 300 muss ’ @0279, 1942 . 5g ‘2‘} ea 1“ ozsb Ewr 723393 1f} M i )2. \ W‘ ’ a. . . 1011 f . MAP NO 7 a» a a NOTES FLYING THE WEATHER Cold fronts have family resemblances—each one has most of the general characteristics you discovered when studying maps Nos. 5' and 6. List these general characteristics: ' Fronts, however, don’t fit any blueprint. Each one is a “rugged individualist,”—with some variations from the general pattern. These variations result from the differing characteristics of the air masses involved. Maps Nos. 7 and 8 present two cold fronts with “personality.” In later lessons you may plan flights through these fronts. On map No. 7 (July 19, 1942), mT air moving northward from the gulf meets mP air drifting southeastward. The mP is colder. About how much colder? ____________________ Both are labeled “k”—they are being warmed by the warm land over which they move. The moist mT air, advancing over warm land, becomes less and less stable as its lower portions heat. (It becomes conditionally unstable, if you must be exact.) Along the front, where this air is forced up over the advancing colder air, the moist warm air “boils up” into squall line thunderstorms—a definite flying hazard. Map No. 8 (November 25, 1942), shows a much different type of cold front. Two surges of cP air come southward off cold Canadian plains. The first surge of advancing air is only slightly colder than the dry- cP air that it underruns and displaces; its front—extending from Canada to Colorado—causes little or no precipitation. The second surge brings colder air. It causes what we call a secondary cold front. Such fronts are common. Notice that a secondary cold front does not have a pronounced wind shift line—many have none at all. Why? __________________ ________________________________________________________ Also, many secondary cold fronts have only weak pressure troughs. But they often bring decidedly cold waves. Is the warmer air mass on Map No. 8 stable or unstable? __________ State your evidence: __________________________________________ Look now at Map No. 9. The isobars, and a cold front, have been omitted from the area between the Great Lakes and the Gulf of Mexico. Draw the cold front on the map, using the method you have learned for locating cold fronts. After completing the cold front, draw in the missing isobars. Label any high- or low-pressure area your isobars reveal. Then shade the precipitation areas—or color them green. On this map (March 11, 1942), the area from the Great Lakes to the Gulf has no warm front. ., ma . so 088 Novemberfilm 395mm ‘ MAP NO. 3 i? t? i? NOTES UNIT 3—COLD FRONT WEATHER 23 115’ 110° 105° 100° 95' 90" 85° 75° 1014 10"" 1008 1005 49!. 40°,w 35‘ 14103 ¢ ‘ ’ 2%5 2,30 427* -2812 391 64210 43fi 4:)2‘; _ g. 321.35. 3111f; 30' ' UNITED STATES NAVY- 25' / March 71,7943 - 0230 [WT , ' , x 03. “’r 65"; SCALE ’ , l ,, 63‘1153/ 300 MILES " a; ' 5: 120° 115° 110' 105° 100° 05° 90° 35° 80° 75‘ MAP NO. 9 24 UNIT 4 WARM FRONT WEATHER Map No. 10 (December 18, 1942), has an excellent example of warm front weather—you will soon be asked to draw in the warm front. The cold front on this map is weak~weak because the advancing air mass (along the cold front) is not much colder than the air it dis- places; so the map shows no difficult cold front weather. The oc- clusion causes most of the precipitation over Pennsylvania; the warm front causes the precipitation to the cast. The accompanying drawing presents a cross section profile of the warm front weather of Map No. 10—from Virginia to Maine. It shows the warm front to be on the surface not far north of New York. Draw the warm front on Map No. 10 extending it from the occluded front to over the ocean. Use the following considerations in locating a warm front: (1) A wind shift at the surface.—The warm front on Map No. 10 has a decided wind shift. Along many warm fronts, however, little or no wind shift can be detected. (2) Temperature change.-——The warm front on Map No. 10 brings a temperature change, but you would have difficulty locating the front if considering this characteristic alone. Along most warm fronts much mixing of the two air masses causes a wide zone of temperature transition. (Pronounced cold fronts may cause tem- perature to drop many degrees in a few minutes; few warm fronts bring such abrupt temperature rise.) (3) Pressure trough and pressure tendency change—A pressure trough exists along the warm front on Map N o. 10; but commonly a warm front pressure trough is not as well developed as a cold front trough—in many cases it just doesn’t exist. Likewise, pressure tend- ency, though very useful in locating cold fronts, is less useful in locating warm fronts. Ahead of a warm front, pressure falls; behind it, pressure may continue to fall—owing to approach of a cold front or possibly the storm center. (4) Cloud formations and precipitation give the best information about the location of the warm front. They are the chief charac- teristics of a warm front, and greatly affect flying. As advancing warm moist air, rising to go over the wedge of colder air, moves up the sloping warm front surface (see cross section for Map No. 10), its moisture condenses and a broad cloud belt develops. These clouds extend far ahead of the surface ernt and may also extend well back of it (see cross section). The cross section shows the cloud sequence as it actually existed on December 18, 1942. It often varies from this pattern. When the ascending warm air is very stable the usual cloud sequence, as the front approaches, is (a) cirrus, (b) cirro stratus, (c) alto-stratus (with drizzle starting), (d) nimbo—stratus (and rain)—-“tailing” out into (e) stratus. Stable air—stratiform clouds. Precipitation may fall steadily from the thick alto-stratus and nimbo-stratus. When the ascending warm air is unstable, cumuli-form clouds develop. The sequence then is generally something like this: (a) cirrus, (b) cirro-cumulus, (c) alto-cumulus, (d) cumulo-nimbus— “tailing” out into (e) strato-cumulus. Precipitation may come in showers—often thundershowers. Rain falling from the warmer air into and through the colder air below the frontal surface frequently causes fog or a layer of low FLYING THE WEATHER \Ni x ‘ ‘wsmssw i‘ ““\ \\ ,\\\\\\\\\\\ . - \ Assess“ t\§ .\\ «xxxxx \ \x a \ Wm WNW . “me-i \\ \ ‘ ~ ‘ ) E i W a 3 clouds in the cold air. (The rain provides the moisture required to bring the cold air to saturation.) These lower clouds—generally low stratus—quickly and greatly reduce ceilings and visibilities. *t‘rvfr Return now to Map No. 6, on which you drew “your first cold front.” Locate the warm front on that map. Start at the station of lowest pressure, 998.0 millibars. Looking eastward from this point, you find (1) a Wind shift line which is also (2) a temperature change line, and (3) a pressure trough. The wind from the south strikes the line with greater force and directness; the warm air mass is advancing. This is the warm front—it continues to a point in western Pennsyl- vania—draw it on the map. Now, make the isobars “kink” where they cross it. From the end of the warm front (in western Pennsylvania) a sta- tionary front extends southeastward. This is a front along which neither air mass is advancing. On hand-drawn maps, stationary fronts are drawn with alternating blue and red dashes. Draw the stationary front on this map. ' NOTES UNIT 4—WARM FRONT WEATHER 25 2 5,000’— 2 5,000’_ \ cm ' / E g SCALE // w ,7 / wt 3 // 20,ooo’— § “ . 20,000’... 700 ”71/25 fiar/zom‘a/ - ' i ALTO-STRATUS (Min) \.. . W (v > "Qj W ‘» I :5,ooo’— '\—-\._\ . _ W 7 »©_“;_W 7 rv . 521;; 15,000— “"“—I0°C __ , Gagunmcumuws * in??? “‘\-~ ’ “—7 Jwfimth AIJ'O-STRATUS 5;}_ \~ ._ I o (1.;4.’ T': £35.)" agwfiw‘vv :‘ ’ ‘\~_ -- -— __ _IO°C \ < _ , fl?- .5.) '~ ' . w” 7" 7 . w -222, _.\§, , , '\- #737: ‘—‘[ ' s . ‘ - r 10,000 _ \-\- _ fl , 2 X‘i _ I0,000 __ §"“o°c ~~ ALTO-STRATUSCMIc/c) 3174:5122. \-—--\, 2 or N IMBO— STRATU _ ‘ 4/ ‘ 7' ‘ I _" ' A I 5,000 '_ /'/ _, ,, STRATUS ' 5'°°° —- /, _x 2.2:: ' 1f (NIMBo—srRA-rus -/’ 0; -* r a T:- <~\' ’ ’Q : vi ' A. T - 0°C‘~ a'- . W . 4;: ."‘A" 1"! I . A — J 37 035 34 04: 32 04: 3| 04: 23 4 058 20 074 :2 w 7 é, 091 —7 04: 9 —24\ 9 —34\_ 946 —34 4am —42 Hex — 44\_ “6* — 50\ 088 9 +4/ +I4/ *- 26 22 *I 27 3‘0” .14 28 I?“ .n 22 3’ .l5 I8 Es" * .07 322- —26‘\ —6 44M RICHMOND WASHINGTON PHILADELPHIA NEW YORK HARTFORD BOSTON PORTLAND BANGOR CARIBOU FIGURE 4A.—Cross-Scction (Virginia to Maine) showing warm front weather, December 18, 1942. 020121942 0230 E WT §0AL§ 300 MILES MAP NO. 10 26 Each of the four sectional maps on the facing page contains some warm front weather. Map No. 1-1 (January 8, 1942), shows winter mP air—moist and comparatively warm—advancing northeastward over northern Cali- fornia. It overruns cP air along a warm front that extends from Portland, Oreg., to Salt Lake City, Utah. Notice how rains extend southward along the coast; these are not of frontal origin. Notice, also, how the Cascade Mountains retard advance of the front: Moun- tains help cause prolonged winter rains along the Pacific northwest coaSt—they force air blowing from the ocean to climb, cool, and lose its moisture; and they also retard advance of fronts, causing frontal weather to remain over the region for periods of several days at a time. Shade or color the precipitation area on this map. Why is the air mass northwest of the warm front indicated as mP over 0?? _____________________________________________________ Map No. 12 (April 30, 1942), is incomplete. It shows mT air moving from the south and meeting cP air that moves from the north. When the two air masses meet over eastern Colorado, a small cyclonic wave has developed. Notice that this frontal activity has produced a low pressure center—and notice that the wave (like all young waves) is composed of a cold front and a warm front extending from the low. Across Nebraska and South Dakota the cold air mass is advancing and “squall line” thunderstorms rage along the cold front. Notice that here, as along all well developed “squall lines,” the cold air mass is much colder than the air it displaces. A warm front extends eastward from North Dakota. Draw it on the map, locating it by studying ( 1) wind shift—if any, (2) temperature line or transition zone, (3) pressure trough, and (4) cloud and precipitation area. (Direction of winds on the two sides of this front suggest that it is a warm front—that the warmer air mass is advancing, displacing the colder air mass. Aerologists learn which air mass is advancing by noting location of the front on preceding maps.) Complete the isobars and shade or color the precipitation area. Is the warm air that ascends along this front stable or unstable? Map No. 13 (May 22, 1942) has a warm front extending from central North Carolina. Which direction? Draw it on the map. Complete the isobars. Shade or color the precipitation area. Along this front, which air mass brings most of the moisture that provides the precipitation? _____________________________________ What causes the fog in the colder air mass? FLYING THE WEATHER Map. No. 14 (April 9, 1942) shows great temperature differences between the two clashing air masses. On the map, label the warmer of the two air masses. Give the approximate temperature difference between southern Missouri and eastern Tennessee: _________________ ____________________ Between eastern Tennessee and southern Virginia: ____________________________ Between the central Gulf coast (New Orleans and Mobile) and the western Gulf coast (Galveston) : _________________ Shade or color the precipitation area. Notice that precipitation precedes the cold front (this is characteristic), precedes the warm front in a wider belt (this is characteristic), and surrounds the occluded front in a still wider belt (this, also, is characteristic). 7% if? i‘r NOTES NOTES UNIT 4—WARM FRONT WEATHER 27 \011 55 2 57°23 1°26 ”23 L©W 43% ‘ M ‘33 “6° 1020” «cp 1on I ‘ 6043122 JAN. 8, 1942 +8/ 4 , egg-2m MAY 22, 1942 0230 5m 53 W ig J25, um mz‘ 5" 26;"; . 1°" 0230 ewr y“ / / i g . MAP N0. 11 SCALE MAP NO. 13 300 MILES N, a? ’52 g n “6 b 45/4 106 E,“ «'05 If»? >1 i y; 7020 \ cpw (WW mm “K 2 f 42" ’4 "”4 4 ~o» 41163544 129 4g “"27 ".’.._/\ ’ -(0 3 5 7- , 31 18 > 6" ”33 w E6493” We 32255.34 ‘ * 5450 34‘4”” ”W‘ 2-; 2 " W ?- 25 * \éfi ska/Zfli‘ 79:34 A Ae’érzz ‘ f“ A , ; *‘ . “M” M 4, A ' ‘ ‘ 43 129 Egan ’ 4g§qg33137 8 40 +0” ¢P 35‘, “3° -T 15?} a; f 53‘ x I 1 case 66 4.1124 ( 67 +33,— 5.. 4% f: 03] ' 59705?l .9! \ 6%,5027 3 g3?“ 25?” w J «y A %- hrkh 9, 39435 1 05 mos 31011 1014 996 999 \002 MAP NO. 12 MAP NO. 14 28 UNIT 5 THE MOVEMENT OF WEATHER l/Veather moves—It moves because air masses and fronts, which bring weather, move. Storm areas along the fronts advance, in gen- eral, from west to east across regions of the middle latitudes———carried in that direction by the prevailing westerly currents of the Wind FLYING THE WEATHER aloft. Over North America most frontal storms move along a general track that resembles a giant V with rounded bottom. The V extends from the Aleutian Island area of Alaska southeastward to the Missis- sippi Valley, then (curving broadly) northeastward to the Icelandic area of the North Atlantic. Today’s weather at Edmonton and Medicine Hat may reach Omaha tomorrow; today’s Weather in Ken- tucky and Tennessee is New England bound. I/l'eather moves in irregular pattern and with variable speed.—The frontal storms of the middle latitudes develop and advance along the polar front—which is that irregular and changing front between polar air masses and tropical air masses, a front along which polar air some- times surges far south and tropical air sometimes surges far north. These surges make storm tracks irregular and speed of movement variable. Also, weather does not everywhere move with the same average speed. In California, which lies southwest of most of the polar front activity of this continent, and in mountain areas where frontal advance is often retarded by the ranges, weather occasionally stands still—for a while. While weather moves it changes—As an air mass or frontal storm . advances, the weather within it changes. Moving air, like “standing” air, changes owing to diurnal heating and cooling—air becomes more unstable during the day, more stable during the night; and moving air also changes because air masses acquire characteristics of the surfaces EXPLANATION OF SYMBOL WEATHER REPORTSl over which they move—for example, a “dry” front changes to a “wet” front when it arrives near a source of in-feeding warm maritime air. Because weather moves and changes, sequence reports are important to pilots—At naval air stations, weather maps are drawn every 6 hours. When a pilot, planning a continental or coastwise flight, studies a weather map that is more than an hour old, he knows that the weather probably has moved and changed (at least a little) since the map was drawn. To get the latest information he reads sequence weather reports—of stations along his route. Sequence reports are transmitted hourly, in teletype form, to stations on airways of the United States. Every pilot should be able to read them, understanding the various data as they apply to safety factors for flight. Weather information must be sent over teletype circuits in con- . densed form, with use of abbreviations and symbols. The self—explana- tory chart below gives all information necessary for reading the basic content of any sequence report. (Special data is sometimes included— after the “remarks” or “altimeter setting”—but is intended primarily for aerologists.) While in the air, flying airways of the United States, pilots may receive radioed hourly weather reports. During wartime these radioed reports are coded; and pilots carry decoding sheets. The teletype sequence reports, such as presented below, may be consulted at air bases, while planningfiights. WA N SPL 1624E E30 EB 15 @2VT—R—BD— 152/68/60—>\. 18—? 1618E/996/+ GBNW | .__i L_] [—1 | | l.__|| |__, || ||____|| l | i_l J L 1| II I Classi T e of _ The re rt given here Station fication £50” Time Ceiling Sky ViSibility Weather Obstructions to vision 332:2320 Temperature Dew point Wind Altimeter setting Remarks as ”01,015. deciphered ashington; . _ _ y ’ . ’ ' . . . . ' _ “‘ Satisfactory for in- Stamm Ceiling is given Absence of a symbol for sky in- Visibility is giv- R—Light rain. F——Damp haze. Barometric Temperature Dew point is The wind direction is indicated by Altimeter set- Remarks are in strument flight _ . in hundreds of dicates that precipitation or en in miles R Moderate rain. F— Light fog. pressure is is given in given in de- arrows, as follows: ting is indi- authorized En— only; Lists of station names and their repre- feet: 35 indi- obstructions to Vision make and/or frac- R+Heavy rain. F Moderate fog. indicated by degrees Fah- grees Fah- iNorth. cated by three glish abbrevi- Special report; sentative call lettersare posted on most cates 3, 500 ft; the sky unobservable. . tions of miles: S—Light snow. F+ Thick fog. three fig- renheit. renheit, in i. {North-northeast. figures, repre- ations and tel- 4:24 p. in. eastern airport weather station bulletin boards. 3 indicates 300 The sky condition is indicated 6 .indicates' 6 S Moderate snow. FF Dense fog. ares—tens, Temperatures exactly the 1! Northeast. senting the etype Symbols. war time; , ' ft.; etc. by the following symbols un- miles; 21/2 m- S+Heavy snow. . GF— Light ground fog. units, and below zero same way as e-(East-northeast. inch and ham The teletype Ceiling 3,000 ft. Classification T h e f' 1 g u re less the condition given above dieates 2 and ZR—Light freezing rain. GF Moderate ground fog. tenths of Fahrenheit temperature. e—East. dredth of an symbols used estimated; naught (0) is is present. 1/2 miles,etc. ZR Moderate freezing rain. GF+ Thick ground fog. millibarsin- have a min- eREast-southeast. inch of pres- are shown on Overcast, lower The symbols C, N andX are used to used when the Clear Absence of_a'flg- ZR+Heavy freezing rain. GFF Dense ground fog. valved: 152 us sign (—-) l\Southeast. sure2000means this chart. scattered clouds classfly weather conditions at airports ceiling is zero Scattered clouds. ure for visibil- —Light drizzle. IF— Light ice fog. means 1015- preceding TRSouth—southeast. 30.00 in.; 925 Lists of the at 1,500 ft.; located within airway traffic control (below 51 ft.). (11) Broken clouds. ity indicates L Moderate drizzle. IF Moderate ice fog. .2 mb; 995 them. Zero 1‘ South. means 29.25 abbreviations Visibility 2 miles, zones which are sending the reports. Absence of aceil- $ Overcast. that the Visi- L+Heavy drizzle. IF+ Thick ice fog. means 999.5 Fahrenheit TilSouth-southwest. in.; 015 means are available variable; Those stations outSide the control zones ing figure_ 'ln- (1)] High scattered. bility is 10 ZL—Light freezing drizzle. IFF Dense ice fog. m b ; 0 2 6 is entered as )Southwest. 30.15 in. at most air- Mild thunder- do not send the classification symbol dicates ceiling 013/ High broken. miles or more. ZL Moderate freezing drizzle. H Hazy. means 1002- “0". —>/‘West-southwest. port weather storm, light rain; bill these conditions can be learned it n l 1 1M” d - $/ High overcast. The letter V fol- ZL+Heavy freezing drizzle. K— Light smoke. .6 mb; etc. —)West. stations. Light blowing (11153; from the remainder of the report. (above 9,750 $01) Overcast, lower broken. lowing the fig- E—Light sleet. K Moderate smoke. —)\. West-northwest. Barometric pres- C: Satisfactory for contact flight. vft.) . $0) Overcast, lower scattered. ure for visibil- E Moderate sleet. K+ Thick smoke. \Northwest. sure 1,015.2 mb.; N: Requiring observance of instrument “hen the height (DOD Broken, lower broken. ity indicates E+Heavy sleet. D— Light dust. .L\.North-northwest. Missing data Temperatures 68° fligh t rules is estimated the (D0) Broken, lower scattered. that the visi- —Light hail. D Moderate dust. Wind ”8106“” is given in miles per F- X: Take-off and landing suspended letter E pre- (DOD Scattered, lower broken. bility is fluc- A Moderate hail. D+ Thick dust. hour, “calm” being indicated by Dcw point 60° 1". T cedes the ceil- (DO) Scattered, lower scattered. tuatmg rapid- A+Heavy hail. . BS— Light blowing snow. the letter “C". The letter “E" Information normally included in Wind, west-north- ype of report Airfigufgggge: (+) 63/01) Héglh overcast, lower brok- ly.] and 1is 2 fig—Ifiiggt small haililh l gg+ TMiidlerl-ble blowing snow “allowing the velocity shows that a report, but for some reason west 18 mph, . u , 1 . . mi es or ess. o era e sma ai . ic owing snow. t e ve ocity is estimated. A min- missm , is sometimes re laced fresh ts; mod- SPL, meaning special report, ’ appears preceding the 63/0) High overcast, lower scat- AP+Heavy small ball. GS— Light drifting snow. us sign (—) following the velocity by theglettei' “M” entgredlin the crate gVicl'sind shift when crucial changes have occurred in weather conditions since the last re- port. The absence of SPL indicates an observa- tion where no crucial changes have oc- curred Since the last transmitted ob- servation. LCL meaning “local extra observation,” appears only on reports sent over local circuits. Such reports are made every 15 minutes during periods of low ceiling and/or visibility. Time of report Time is given in figures based on the 24- hour cock followed by a lettershowing the standard of time used: 0630 C, for example, means 0630 Central WarTime. ceiling figure indicates that the ceiling is higher than the figure given. The letter V fol- lowing the cell- ing figure indi- cates a ceiling that is variable (changeable) and below 2,000 (DIG) Highe broken, lower brok- /CD Hg}; broken, lower scat- (D/GD High scattered, lower brok- CD/(D 11:ine zcattered, lower seat- The plus (+) or minus (— ) sign receding the cloudiness sym~ ol indicates “dark" and “thin", respectively. Height of lower scattered clouds is indicated by the entry of a figure, representing hundreds of feet, immediately preceding the scattered clouds symbol. SP—Light snow pellets. SP Moderate snow ilets. SP+Heavy snow pel ets SQ—Mild snow squall. SQ Moderate snow squall. SQ+Severe snow squall. RQ—Mild rain squall. RQ Moderate rain squall. RQ+Severe rain squall. —Mild thunderstorm. T Moderate thunderstorm. T+Severe thunderstorm. SW—Light snow showers. SW Moderate snow showers. SW+Heavy snow showers. RW— —Light rain showers. RW Moderate rain showers. RW+Heav rain showers. TORNAD (always written out in full). GS Moderate drifting snow. Thick drifting snow. Light blowing dust. BD Moderate blowing dust. Thick blowing dust. Light blowing sand. Moderate blowing sand Thick blowing sand. indicates “fresh gusts"; a plus sign (+) indicates “strong gusts". No minus or plus sign means the wind is steady. An arrow following the velocity item indicates a recent wind shift at the station. The arrow shows the wind direction before the shift and is followed by figures and letter' in- dicating what time the wind shift occurred: [110150 means that the wind shifted from the southwest at 1015 Central War Time. Follow- ing the standard-of-time letter, intensity of the shift is indicated by a minus (—) sign for “mild”, ab- sence of a sign for “moderate", or a plus sign (+) for “severe”. report in place of the missing data. l Adapted from table published by U. S. Department of Commerce Weather Bureau. from the south at 4:18 p. m., east- ern standard time; ‘ Alztgmeter setting, .96 in.; Dark to the north- west. 4N EXERCISE UNIT S—THE MOVEMENT OF WEATHER Decode the following teletype sequence reports, using the blank table on this page. While performing this decoding exercise you may refer, when necessary, to the EXPLANATION OF SYMBOL WEATHER REPORTS. FT C SPL ESOEB/(DR— 051/59/52 T‘\9/967/ OCNL INTMT R— RANOT BRONO WMR SPL 50$40CD 115/50/46'\12/982/ BINOVC PCPN ENDED 1327P PA C SPL E3001) 054/51/45 4—12/972/ CLDS TPG MTNS NH E20®R— 081/55/53'\14/975/ RGD CLDS TPG MTNS PCPN VERY LGT TZB OORF+ 054/40/40T'\18+/971 BU C El5$® 091/56/54 T8/979/ BINOVC BD C ESOGB/GD 071/62/45 T'\10/972/ STMG OVR MTNS S AND W NH SPL E16®R— 088/52/51'\11/979 CLDS TPG MTNS PCPN VERY LGT LA C 10CD9 65/57/16/SCUD 4HND PIREPS TOVC ABV 14THSD E HB C SPL E10$0D3R—- 098/56/53T\15/981/CIG AND VSBY E‘XTRMLY VRBL OY N SPL 869 088/57/544—/l3E/978/BINOVC CIG HIR SEAWARD OA C APL E4OEB/(ID 054/55/49\4/968/LOW SCUD SW TO NW HRZN SZ X (ID/ 1/16GF+K— 061/48/4816/070 GF 50FT THK CN X E6693/4S—F— 091/30/29T'\8/977/SNW CIG SV E25GD8 l22/37/30—->15——/ 987/ WND SHFTD GRDLY NO X Cl)/18(Dl/4GF+K+ 260/55/520/029/FOG DRIFTING AROUND FG SPL E126®7S~ 34/29—>\19—~/BINOVC OCNL MDT SNW NWD CT N E12690D1VSW— 220/23/19 —v23+/013/ VSBY VRBL 3/4 TO 3 BF SPL E30(]D7 l66/30/22—>\,18/999 HA 116938— 244/20/17—>\.19-/018/BINOVC 29 Station Flight classifica- tion Ceiling Visibil- ity Weather Obstructions to vision Barometric pressure Tem- perature Wind Altimeter setting FT (Fresno) ______________________ WMR (Muroc Lake) ______________ PA (Palmdale) ____________________ NH (Newhall) ____________________ TZB (Sandberg) __________________ BU (Burbank) ____________________ BD (Bakersfield) __________________ NH (Newhall) ____________________ LA (Los Angeles) _________________ HB (Long Beach) ................. OY (Santa Barbara); ............. OA (Oakland) ____________________ SZ (Sacramento) __________________ CN (Concord, N. H.) ______________ CV (Sunbury, Pa.) ________________ NO (New Orleans) ________________ FG (Pittsfield, Mass) ______________ CT (Youngstown, Ohio) ___________ BF (Bellefonte, Pa.) ............... HA (Hayesville, Ohio) _____________ ______________________ 534786 0 - 43 - 5 30 FLYING THE WEATHER 100° 95" 90° 85° ‘2 250 1029 1025 jzgflnzj 10:7 1014 mu 2 1. 2:5, ’9 1,. 1-23 I ’7. 6297 2x]: +2////// . V['16/l14\.;~/ 0/ 237 E f; V+20C E 23 , ’ 220 /P . sewer 0 / 3’ M. -l 33 0/ TW 75 o’/ 80“ 1009 1001 005 75° 9‘59 9°)“ 70° 993 ' UNITED STATES NAVY- February 24, 7943 - 0230 E W 7' 1014 SCALE ' 101 300 MILES 1 '0” lo: 4 mm 13° 110° 105° 100° 95° 90° 05° 80° 75° 70° 65° MAP NO. 15 Maps Nos. 15, 17, and 19 show weather at 6-hour intervals on February 24, 1943. Notice that a cold cP air mass advances across eastern United States, displacing warmer cP air. A still colder cA air mass pushes south from the Canadian plains, producing a secondary cold front. In this exercise you will map the movement of the first (the primary) cold front. - Map No. 15 shows weather conditions at 0230 EWT. On this page are teletype sequence reports for the hour 0530 EWT. For the region they cover, these reports show weather conditions 3 hours after the time of the map. Occasionally, when an aerologist or pilot has sequence reports but no recent weather map, he uses the sequence report data to draw a weather map. You can do that now: draw Map No. 16. Using data from the following sequence reports, enter station models on the base map. Sequence reports do not contain full information for complete station models. They do, however, give the essential information: ceiling, total amount of clouds (sky), visibility, present weather (and obstructions to vision), barometric pressure, tempera- ture, dew point, and wind direction and velocity. After entering station models on Map No. 16 draw in the cold front. (Locate the front in the manner learned in unit 3.) Now draw the isobars across the area you have mapped, remembering to “kink” them where they cross the front. 240530E BJ N SPL 1669 11/4R—F—K— 020/43/42/‘6/957 AZ 0 (9/611 047/48/41122/965 LG C —e/4K— 088/40/38T'\7/978 PG C —aa/4K— 088/49/41 8/978 WA C —®/6K— 091/57/47/15/979 R0 -ea/4oos lO5/58/49—v6/986 KX C 60—0/(1) 122/60/47/‘16/989 NA C 650) 098/60/511/16/982/0VOD RW C -(]D/7 122/55/49T8/988 HI 45634R— K— 081/57/50—b/‘5/976 EK — (N550) 081/54/43 T \8/979 PT C SPL 306310®8R— 051/54/481/‘14-l968 FW N 7&3503F—K— 088/36/35\.l6/976 CV C SPL 17$3F-K— 051/43/4l\l3/966 ID N 966F—‘ 129/39/361\.17/989 EV C SPL 11$3H 105/42/37\.13/983 / CO C E60® 4K-— 054/53/51/‘13/969/ INTMT R- BF SPL 40$”) SRW— 05l/50/4l—)-) 12/967 CC C 30(D 061/58/51/‘5/970 GW N SPL E75—®1K~— 132/56/52/‘13/992/ CLDNs OCNLY 99 it {I ‘9! In latitude 40° N, how many miles did the cold front move from 0230 to 0530? __________ (See scale of miles on Map N o. 16, but remember that Map N o. 15 is on a different scale.) How many miles did the cold front move from 0530 to 0830 (see Map No. 17)? .......... UNIT S—THE MOVEMENT 0F WEATHER MAP NO. 16 31' 32 FLYING THE WEATHER 130° 125° 120° 115° 110° 105° 100° 95° 90° 85° 80° 75° 70° 65° 60° 55° 50° 4.5]. Q ‘ [026 I023 [020 50‘ ‘ I L T3 102‘ 33’ 320 36‘ ’2 < M\ 33208; 7’22©$}?3 0L 2‘! 2 501g: MS) 3/9 37/91“ \ .T ‘ 45° 1 i ‘ ’84 I \a—‘I‘oI’Z/l /. ’//,,/, a. 268 . ’1'2 , v 4°' 0% 16% ° 5 ,/,,’ / H 295/” /%”’/////// 7,};23/ '2 / WM”? ///// 5’2 249% ”04/ //{z[' / 33%; gfi’, , 31 ’2' ’ 35. 2365-4, .1 \ 35' $125? 42 ll MPK I01; 4936a E9; \/ I 70/ 27(1‘3 , 4,6246] 486,42 1 20 4530 ‘2‘ ,223 '3 I _ 27% , 40:4 30. :6- 25 i 30' ’ ' 26 £332; (Stu-go ¥ \ %%°/ ° UNITED STATES NAVY° February241943 - 0830 E W7” 25° v 25° am" ‘53, 5m 1014 6275 300 muss I , 1014 . 1i 115° 110° 105° 100° ' 95° 75° 70° 65° ’ MAP NO. 17 Using information contained in the sequence reports for 1130 EWT, draw Map No. 18. Enter station models, draw in the cold front and draw the isobars. 241130E 10$®4SW—K— 080/34/31\.l4/976 E4063/(D 21/4RW—F— 031/46/43/'\14+/960 (ID/60 (D2K— 064/49/42'\12/971 o/sosx— 068/60/504/12/972 E6063/(D3H 085/60/52/7'17/977 Esoeaaom 105/61/484/15/985/ BINOVC ooos l32/63/53—>/'20+/993 E15e11/2K— 159/45/401\.14—-/999/ PIREPS TOVC NA 40 MSL e/4HK— 105/64/54T/‘11/983 E35$®’6K— 098/62/55/14—l981 SPL zoemw— 091/56/48—>/‘l3/981/ BINOVC SPL+18$10®254RW~ 081/49/43\.19+/976 SPL 1259 l66/3l/281\.ll/000 9697 135/35/301\.18/990 E16630!) 792%K— 119/39/37 1 \24/987 14€93K— l42/42/36\.17/993 E35CD/(D8 058/55/51/18/968 ~o/3K— 132/65/52/‘18/992 In latitude 40° N., how many miles did the cold front move from 0830 to l 130? __________ From 1130 to 1430? __________ Briefly describe the weather changes at .......... for the period 0230 to 1430: --__--_-___-_-_----_---_, ........................ ________________________________________________________ UNIT 5-THE MOVEMENT 0F WEATHER MAP N0. 13 34 ‘ FLYING THE WEATHER 80° 45° , 50‘ 50° “0370 figs—.1032 45° 45° as fo\ 40° / 30 40° 2_ 48 // 3 W g 7133 756 6. 3 ///¢ 2 V 38w $1005? 20 , ' Io -- 1.- ’ . 5' ””0" ////' 2 *6, ' 7%Vo&i / ° ///,,’/“’7// 2% 333:1, & 32L) ”26v ‘l % 424234 6 4 a 35° £4; .29 +2121 232E33— ‘235-6/ 35 MP“ 7////2 Z9 2‘35 £1530 £0 132 ,0 20 2PM“ 14 19 64 1129‘ 4%‘133f 77g ’ 2 30 30° . 30° ° UNITED STATES NAVY ° February 24, I943 - I430 E W 7' 25° 2 25. ’0’]; SCALE . . \ 300 muss o 1 1017 1020 . ‘ _ ._ _ 10" _ 115° 110° ' 105° 100° 85° 90° 35° 50° 75° 70° 65° MAP NO. 19 For further following: ANOTHER EXERCISE UNIT 5—THE MOVEMENT OF WEATHER practice in reading teletype sequence reports, decode the LI C10®3F— 210/28/23\.2l/014/BRM RSG RPDLY WJ N SPL ESEBGDSZL—F— 196/26/26/15/009/CIG INDFNT ZL— INTMT UR N SPL 4 ZL— 203/24/241/6/011/PCPN VERY LGT RF SPL 01/8F+ 132/35/3596/987/F+ MOVD IN RPDLY TB 5GBGD8TR— 115/64/64/‘15/998/ T DSNT FQT LTGN ALL QUADS 0U —-(ID/35® 183/78/71 T \12/006/OCNL LTGN SW NW QUADS XM SPL8$3/4L—F—— 108/48/47\.5/984/PCPN LGT INTMT ZQ C 356958— 271/9/618/027/BINOVC FC C E2OGD10CD8 173/74/71'\6/003/SCUD 5HND FT UM N9$2K—F— 115/64/62 T 3/987/K ALF MS X E4®3TRW—F— 132/70/69T /'9/992/T IN S WKE E3EBI/2F 163/68/67 T \17/000/FOG CIG GU 11$3/4VS— 186/22/201\12/003/SNW CIG VSBL 1/2 TO 11/2 KK SPL—GD/50CD3S— 184/17/12<—/14/15—(D CLDNS CHGBL EK SPL E3069/(ID 132/52/50‘\7/993/12(D CLDS TPG RDGS W HX X E5€B3/4VRL—F—K— 180/35/34C/004/VSBY VRBL 5/8 TO 1 WN SPL E10®7TR— 159/62/61 T /'11/000 T SW AND NE LTNG CLD TO GND AS SPL E1063®2RF~ 156/63/63 T 9/999/T DSIPTD AG C SPL E25®QD6RW— 132/65/65 T 8/995/ DRK S LTNG SE KT E4EBQD3R— K—139/62/59T/‘27+/993/ OCNLY RW+ VSBY VRBL 1 TO 3 35 Station Flight classifica- tion Type of report Time of report Ceiling Visibil- ity Weather Obstructions to vision Barometric pressure Temp- erature Altimeter setting LI (Little Rock) __________________ WJ (Westfield, Mass.) UR (Manchester, N. H.) RF (Cove Valley, Pa.) TB (Butler, Ga.) 0U (Melbourne, Fla.) _____________ XM (Smithville, Tenn.) ZQ (Presque Isle, Maine) ___________ FC (Cross City, Fla.) ______________ UM (Meridian, Miss.) MS (Mobile, Ala.) _________________ WKE (New Orleans) ______________ GU (Gladwyn, Mich.) KK (Cadillac, Mich.) EK (Elkins, W. Va.) ______________ HX (Harrisburg, Pa.) ______________ WN (Warrenton, N. C.) AS (Anderson, S. C.) AG (Atlanta, Ga.) KT (Blackstone, Va.) ________ 36 0030 0130 0230 0330 0430 0530 0630 0730 0830 0930 1030 1130 1230 1330 1430 1530 1630 1730 1830 1930 2030 2130 2230 2330 0030 0130 0230 0330 0430 0530 0630 0730 0830 0930 1030 1130 1230 1330 1430 1530 1630 1730 1830 1930 2030 2130 2230 2330 FLYING THE WEATHER Following are listed the hourly observations as placed on the teletype sequence on the Cleveland-Nashville airway. By studying these reports you can learn at What time the cold front of February 24, 1943, passed each of the stations on this airway. On the answer lines above the cross section on the next page, indicate the time when the cold front passed each station. CV CLEVELAND 85$ 037/56/45 T /‘14/962 RARAU SPL 48$IGD7RW— 034/56/56/20/961 RARAU 24$3RW— 034/55/53/‘28/962/ RW OCNLY MDT 32$5RW— 031/54/51/‘20/960 RARAU 20$7 034/53/51-—»\.20/961 RARAU SPL l7$3F—K-— 051/43/41\13/966 RARAU SPL 4$ll/2F-—K—— 064/40/38\.16/971 RARAU 5$2F—K— 078/37/35\18/975/BRM RSG RPDLY RARAU E2$2F— 095/36/341 \14/979 RARAU 6$4F— 112/35/331\15/984 RARAU SPL 8$7 125/35/32114/988 CIG RGD RARAU 9$7 l35/35/301\.18/990/ RARAU 10$8 146/34/291\.17/993 RARAU 14$9 156/34/291\.20/996 RARAU El4$ 163/34/30115/998 RARAU 10$ 163/33/31114/998 RARAU 11$ 176/32/271\.20/002 RARAU 14$ 190/32/25\.l5/005 CIG RGD RARAU E12$ 196/32/251\16/007 CIG RGD RARAU E10$ 207/31/25\.16/010 RARAU 17$S— 213/32/261\.16/013 RARAU SPL 300110170) 220/30/2518/014 RARAU $180) 224/29/23113/015 RARAU 27(1) 227/28/211\.12/016 RARAU OOOOOOOOOOOOZZZNZNOOOOOO HA HAYESVILLE SPL 36$®6RW— 051/55/471/15/967 E70$4RW~ 047/52/49/‘22/966 36$ll/2R— 044/52/50/‘21/965 E$®1R 037/52/51/‘22/963 E12$(1D 1/2R~F—- 031/52/50/‘17/962 14® 037/52/51—>/'17/963 SPL 14$3/4F— 054/43/41—>\15/967 SPL 3$1/2F 064/40/39\.12/970/FOG CIG 3$1/2F 095/36—>\.19/979 SPL 2$1/4F+ 108/35/35\.l5/983 SPL 3$11/4F— 122/33/33l\.l8/986 4$2F— 125/33/321 \22/987 4$/'18——/967 E600D4K— 054/53/51/‘13/969/INTMT R— 16®3K~ 064/52/50—2/‘13/972 E100D21/2K— 075/50/441 \19/975 E10$11/2F— K— 091/43/401\.18/979 6$<1D1R~ F— K— 108/40/381\.23/983 FINO 7$21/4K- 119/39/371\.24/987 SPL 10$3K— 135/38/361\.22/992 6$3R—K— 146/38/361 19/995 12$4R— K— 152/37/341 18/997 SPL 9$7 156/37/331 15/998 , E7$GD7 166/37/331\.16/001/ 12$GDVCD E15$8CD6K— 186/36/321 \15/005 17$8(D5K— 196/35/301 \16/008/ (DVGD E17$8CD5K— 203/34/281\.11/010 / G) VCR) 18$5K— 213/34/281\12/014 22$5K— 220/33/28\.12/016 70$5K— 227/33/281\9/ 018 30$5K— 227/32/25\.10/018 DY DAYTON 40$5RW— 054/55/51/‘20/968 25$4R— 054/52/52/‘15/968 SPL 45$4R—F— 047/52/52/‘15/966 SPL 35$4F— 051/52/51/‘15/967 BINOVC 35(D7 051/50/49/‘16/967 SPL 14(DGF— 064/47/43——>\.16/97l E20<1D6(D5F— 081/40/38\.17/975 SPL 4$2R—F-— 095/39/381'11/980 5$21/2F— 105/38/361 14/982 5$21/4,F— 078/38/36\.l5/985/ CIG RGD SPL 7$11/2L—F— 125/36/36116/988 SPL 7$5L—F- 135/36/35117/991/ PIREPS CIG SPL 9$8 149/36/34118/995 9$9 159/35/34116/998/PIREPS CIG TOVC 50MSL E12$ 176/35/32118/002 13$ 180/34/31121/003 El3$8 190/34/30\13/006 El3$8 196/34/29\.17/008 E15$8 207/33/291\15/010 E40®15(D8 213/32/2918/013 21$8 220/32/2815/015 27$7 227/32/2913/016 27$5K— 230/32/30/‘2/017 27$7 234/32/28\.8/018 0030 0130 0230 0330 0430 0530 0630 0730 0830 0930 1030 , 1130 1230 1330 1430 1530 1630 1730 1830 1930 2030 2130 2230 2330 0030 0130 0230 0330 0430 0530 0630 0730 0830 0930 1030 1130 1230 1330 1430 1530 1630 1730 1830 1930 2030 2130 2230 2330 OOOOOOOOOOOOOOZZOOOQOOOO OOOOOOOOOOOQOOOZOOOQOQOO CC CINCINNATI SPL 6069/(1D8R— 058/62/48 T /'13/969 50$8R— 054/60/50 T /'9/968 46$/GDR— 054/60/511/‘10/968/ INTMT R- 35€B/GD 054/59/51/‘8/968 35$ 054/60/51/‘10/968 30(D 061/58/51/‘5/970 32$4K— 068/56/50—24/972 21$GD4K— 081/51/45\12/976 E20$13/4K— 102/46/401 \10/981 Ell$®2ll4K— 119/43/391\.12/986 12$3K- l25/43/37\10/989/PIREPS CIG 14$3K- 142/42/36\.17/993 E14$4K— l52/41/36\.13/996 18$4K— 163/40/351\.15/999 E18$5K—~ l73/40/34\.16/003 17$5K— 176/40/34\14/004 E17$6K~ 186/39/32\.12/007 E15$GD7 l93/39/31\.11/009 22$7 200/38/31\.10/011 E22$5K— 213/38/30\.14/015 27$7 227/37/29 1 \7/018 E27CID7 230/38/29\.8/019 32$6K— 234/38/291\.5/020/ BINOVC 32$5K— 234/37/29 1 4/020 LV LOUISVILLE 9097R— 068/64/511/15—l973 PCPN INTMT 7097R— 064/63/52T /'15—/972 SPL 709s 068/62/52112/973 45— 98 ________________ T /12/973 5597 068/61/51/‘10/973 E55—97 071/60/52/‘8/974 SPL —<]D7 078/57/50/5/976 SPL E5095K— 095/55/49\.16/980 SPL E50921/4K— 108/46/‘40120/984 2093K— 132/43/36115—/991 PIREPB CIG BRM RSNG RPDLY 1593K— 149/43/361\.15—/997 PIREPS CIG TOVC 25MSL 1695K— 155/43/361 \15/999 E1596 171/42/351\.16/014 E1498 183/41/341\18—/008 1799 183/40/331\.18—/006 E2099 190/41/32115—/008 E259 193/43/34118/009 E2599 200/42/31115/011 E2599 210/41/29\.15/014 E2599 217/40/28116/016 E2097 230/40/28115/020 3097 230/38/29110/020 30007 234/36/2715/021 30007 240/36/27/3/022 UNIT S—THE MOVEMENT OF WEATHER 37 0030 0130 0230 0330 0430 0530 0630 0730 0330 0930 1030 1130 1230 1330 1430 1530 1630 1730 1330 1930 2030 2130 2230 ‘ 2330 SO SMITHS GROVE 63/7 078/61/50T 18/976 63/353037 078/62/50T l8+/976 E3569/GD7 078/60/50 T 21 +/976 (ID/35(ID7 078/60/50T 18/976 (ID/4OGD7 078/59/50T 18/976 50037 078/57/5OT l3—/976 55(D7 085/54/48T 11/978 55(D7 095/53/48T 12/980 ——(]D/CD5K— 115/46/43—915/986/ VSBY 4 SE lOEB21/2I(—- 129/42/39—+15/990 9633I(—— 139/42/38eal5/993 l2EB4I(- 152/43/37—420/ 12694I(—— 163/43/37—+18/998 E12®5K— l73/43/37—r13/003 13694I(—— 183/43/36—+19/005 E13697 186/44/37—->\.14/006 20638 190/44/35 1 \17/007 E2063 196/43/36\11/009 E2069 200/42/34\.15/010 E2563 207/41/33\9/013 2763 217/41/33\310/016 SPL O 220/38/321 10/016 0 230/35/3018/019 O 230/33/29 1 8/019 0030 0130 0230 0330 0430 0530 0630 0730 0830 0930 1030 1130 1230 1330 1430 1530 1630 1730 1830 1930 2030 2130 2230 2330 SCIIKLE I IOO MILES OOOOOOOOOOOZZZOOOOOOOOOO NA NASHVILLE GD/ 095/63/52T /’15/981 E70CD 091/63/52/‘14/981/ 03qu 6569 095/63/51/”l7-—/98l SPL 65G) 091/63/52T /'20+/981 E6501) 095/61/52T /'14/982 650) 098/60/511 /'16/982/CDVQD E55(]D 098/59/51/‘10/982 55(1) 108/58/51/‘13/985 E60—(]D/—GD 115/56/50/‘11/987 E60CD/(1D 125/58/49—>12/990 %$®umK—1mmau\m-mm E15$11/2K—- 159/45/401\14—/999/ PIREPS TOVC 40MSL 1169 21/2I(—— l69/44/39‘y14/002 E12893K— l76/46/39\.l7/004 13$4K— 186/451\.16/007 131393519 186/45/391 \16/007 16635K— 193/45/381 \15/009 E16®5K— 193/45/371 11/010 E27695K— 193/44/37 1 {IO/011 E20690D5K— 207/44/361 11/013 2l€BGI(—— 217/43/34 113/016 236138 220/42/33113/017 2663 227/42/321/13/018 27g; 227/42/331/7/018 FIGURE 5A.—At what time did the cold from of February 24-, 1943, pass each of these stations on the Cleveland-Nashville Airway? ABBREVIATIONS USED IN "REMARKS” IN TELETYPE “Remarks” contained in teletype sequence reports are expressed in regular teletype symbols and in English abbreviations. All regular teletype symbols are explained in Explanation of Symbol Weather Reports, page 28. The English abbreviations can be read by use of a 1373* SEQUENCE REPORTS little imagination. Three sequence report “remarks” that are especially significant to pilots are: ' BRONO——Broadcast not working. RANOT—Range not working. F ILLI—Field and lighting facilities. Study of the following will enable you to read most “remarks”: BIN OVC—Breaks in the overcast. STARS DMLY VSBL~Stars dimly visible. APTNO—Airport traffic control tower radio facilities not oper- ating until further notice. BRM RSG RPDLY—Barometer rising rapidly. CIG VRBL—Ceiling variable. PCPN IN TMT—Precipitation intermittent. CIG RAGD——Ceiling ragged. VSBY VRBL——Visibility variable. GRDL WN D SHFT—Gradual wind shift. TSTM MOVD E—Thunderstorm moved east. FRONT APCHG W—Front approaching from the west. TSTM OVHD OCNL THDR—Thunderstorm overhead, occa- sional thunder. CLDS MOVG RPDLY—Clouds moving rapidly. OCN L SLT—Occasional sleet. ZONOT—Zone not working. SNW WET—Snow wet. ACC IN CRG—Alto-cumulus increasing. THN SPOTS IOVC—Thin spots in overcast. LTN G DSNT N—Lightning in distance to the north. RARAU—Radio range appears unreliable. CAVU—Ceiling and visibility unlimited. Regular teletype symbols are often mixed with the English abbrevi- ations: GF—LOW PLACES~Light ground fog in low places. + 63 OBSCG MTNS—Heavy clouds obscuring mountains. K LYRS ALF—Smoke layers aloft. (ID ALG MTNS—Clouds along mountains. (1D TURBT—Clouds turbulent. OCNL RE—Occasional rain and sleet. VSBY N3—Visibility to north is 3 miles. Pilots’ reports of weather conditions encountered while in flight may be added as remarks to the regular teletype sequence reports. Other pilots, planning their flights, find PIREPS especially valuable and interesting: PIREPS+ICE 15—80 W CX 85—70—Pilot reports heavy icing 15 to 80 miles west of Cheyenne, with base at 7000 feet MSL, top at 8,500 feet MSL. PIREPS—ICE MTNS N BU 115—//-—Pilot reports light icing over mountains north of Burbank, with top at 1 1 ,500 feet MSL, base unknown. PIREPS WN D 315 95 W RK 60——Pilot reports northwest wind of 95 mph west of Bismarck at 6,000 feet. PIREPS TOVC 4O MSL—Pilot reports top of overcast 4,000 feet mean sea level. PIREPS ICE 5—20 N EU //—20——Pilot reports moderate icing 5 to 20 miles north of Eugene, with base at 2,000 feet MSL, top unknown. 38 FLYING THE WEATHER Following are the hourly sequences of airway weather reports along the Cleveland-Washington airway. On the silhouette (on facing page) of this airway, indicate the time that you think the cold front of February 24, 1943, passed each of these stations. 240030E CV C 8563 037/56/45T/‘14/962 AX C E60698 051/54/46T 12/976 TEZ E50€BSK— 061/55/46T/‘7/970 PT NQD/2l/2K— 071/57/48710/973 BQ —$/6 081/52/40/‘7/981 MR 63/ 088/47/40T5/978 WA C —-®/4K— 108/58/43T 13/984 24013012 CV C SPL 48®/0D7RW— 034/56/56/‘20/961 AX C 50$RW—K— 044/52/49/T/‘15/965 TEZ E50633K— 054/55/451/6/968 PT N 85$21/2K— 071/56/44T 10/973 BQ —®/6H 081/53/42T/‘8/980 MR 9/50 (D 085/50/41T8/977 WA C —ClD/4K— 108/56/44110/984 240230E CV C 24$3RW— 034/55/53/28/962/ RW OCNLY MDT AX C E4569 3RW—K— 047/52/48/‘15/966 TEZ E55$3R—-K— 054/52/48T /'10/968 PT C SPL $l3K— 061/56/44110/971 BQ, 63/5H 075/53/38T/‘9/978 MR $l50® 081/53/41T7/976 WA C —(]D/5K— 105/57/46T13/983 240330E CV C 32695RW— 031/54/51/‘20/960 AX C 409315 3RW—K— 041/52/50/‘15/964 TEZ E55692ll2 R—K— 044/52/4ST [11/966 PT C E70€B4R—K— 054/56/441/11/969/ PCPN INTMT BQ 70e3R—H— PUQXTQRQADOXOUU (A garbled report) MR 69/700323 075/53/43112/974 WA C —€B/3K-— 105/56/46T12/983 240430E CV C 20®7 034/53/51—>\20/961 AX C SPL 10®®3R—K— 034/52/49/18—/962/ CIG RGD TEZ E50$3R—K—— 051/52/48T/‘15—l968 PT C 70$4R—K- 051/56/45T/‘15—l968 BQ 75692R—H— 064/51/39—>/'l4/974 MR 63/800) 068/54/441/‘14/973 WA C ®/5K— 098/55/46T 18/981 240530E CV C SPL 17$3F—K— 05l/43/41\.13/966 AX C 10$(1D5R-K— 037/52/49/‘15/963 TEZ 34$3R-K— 044/52/49/‘18/966 PT C SPL 30®10®8R— 051/54/48T/14—/968 BQ (JD/6 061/53/40—>/'16/972 MR 6/800) 064/57/461/‘15/972 WA C —®/6K— 091/57/471‘15/979 240630E CV X SPL 46311/2F—K— 064/40/38\.16/971 AX C SPL 10$GD3K— ‘054/49/47\12/967 TEZ E35634R—K— 051/52/49/‘16/967 PT C SPL 15$(1D3RK— 061/53/50—»12-—/970/ GRDL WND SHFT BQ EB/6H 058/53/43—r/‘19/972/ BINOVC MR 69/8 064/58/46T/‘14/972 WA C ~69/6K— 091/57/471‘20/979/ MOON DIMLY VSB 240730E CV N 5€B2F~K— 078/37/39\.18/975/ BRM RSG RPDLT AX N SPL 7®®21/2K— 064/44/40\.15/970 TEZ E306315CD6R—K— 054/51/49/12/967 R—INTMT PT N SPL 24692Rk— 058/51/50—r/‘11/969/CIG RGD BQ E 35634R—H 058/52/43—>/‘18/971 MR 69/8 064/56/46T12/971 WA C —$/5K— 091/57/48T16/979 240830E CV X E2$2F-— 095/36/341\.14/979 AX X 3EB3/4R—F—K— 081/38/37\.18/975/ TEZ SPL E15$GD6K—~ 061/51/49—r/‘10/970 PT N E25€B®21/4R—K— 058/51/51—r/‘13/969/ 12 E8063 BQ SPL E15$GD3R—-H 064/50/44—r/‘19/971 ’ MR SPL E40635H 061/55/46T10/970 WA N 63/2K— 085/57/50T 17/977 24093OE CV N 663417— 112/35/33l\15/984 AX X 3®1VF—K-— 102/35/35l\.l5.981 TEZ SPL E12®21/2K— 081/47/44\.13/975 PT C (D250)3K— 061/53/50—>/‘14/970 BQ 1363(JD5R—H 071/49/47—r/13/973 MR E35®6H 061/56/48T12/970 WA C GD/3K— 085/57/50T/‘18/977/ /VSB THRU BRKS 241030E CV N SPL 8697 125/35/32114/988/ CIG RGD AX N E7€B/'11/972 BQ El5€BGD6R*H 075/48/4%13/974/ BINOVC PCPN INTMT MR E30696H 064/56/48T12/971 ' WA C E8069/4H— 085/58/521/‘16/977 241130E CV N 9397 135/35/301\.18/990 AX N 10®®21/2F——K— 125/34/301\.13/987 TEZ SPL 7esr—K— 112/38/361\.11/984 PT N SPL *186310021/2RW— 081/49/43\.19 [976 BQ 1569M 075/50/46—vl5/974/ MR Esoeask— 07l/60/50-+/'15/973 WA C E6063/0D3H 085/60/521/‘17/977 241230E CV C 10698 146/34/291\.17/993 AX N SPL 15$(1D21/2K— 129/34/29117’/989 TEZ 11EB5F—K— 122/37/351\.12/987 PT N SPL 5®lVRW—F—K— 098/40/38\.17+/980 BQ 13EBGD7 075/50/45—>13/976 MR E3OGD/(ID 071/62/53\.7/973 WA C 5063/(ID6H 081/65/52/‘23/976 241330E CV C 14699 156/34/291\.20/996 AX N E10®GD21/2K— 146/32/29117/993 TEZ SPL E11690D7 129/37/33l\,10/989 PT N 12®QD11/2VK—- 102/40/36\.17 /981/ E3563 BQ 12$(1D6H 075/51/45—r10/976 MR E3OGB/(ID8 068/64/50/‘11/972 WA C E5OGD6H 081/64/54—r/‘10/976 241430E CV C E1469 163/34/30115 /998 AX C SPL EIOEBQD3K— 149/32/31117/994 TEZ 11637 l32/36/33l\.17+/985 PT C SPL 1263(ID3K—~ 115/40/34\.17 /985 BQ SPL 6®1F— 085/45/43\.13/977 MR E 30$/(ID7 061/67/48—>/‘11/970 WA C E500D6H 071/67/55—a/‘10/ 973 241530E CV C 1069 163/33/31114/998 AX C E10630D3K— 152/30/30117/995 TEZ 1067 135/34/311\13/990 PT C 1683(ID4K— 122/38/32\16-—/987/ E40 BQ 6631F— 088/40/39——>\.19/977 MR E30$l®8 061/64/48—»\12/970 WA C E45GD6H 070/64/55T8/973 241630E CV C 1163 176/32/27l\20/002 AX N SPL 8$GD3K— 163/31/27118/998 TEZ E12696K— 149/33/301\8/994 PT C 16690D4K— 135/37/32\15—/991/E 50 BQ SPL 6®3H 105/37/35\16/981 MR SPL E20®3TR— 068/62/46—924/972/ TSMT OVHD LTNG CLD TO GND WA C E40®7TRW— 068/60/55'\7/972/T MOVG E 241730E CV C 1469 190/32/25\.15/005 CIG RGD AX N E8$GD3K— 176/30/Ml\.14/001 TEZ 15$5K— 159/32/281\.14/997 PT C 14634K— 146/36/30\,.19+/994 BQ SPL 4$®4H 115/36/34\20—/983 MR SPL E40$I®5H 071/57/52—>\12l973 WA C E45®6H 068/59/55/10/972 I 241830E CV C E1263 196/32/25l\16/007 CIG RGH AX N E8®®3K— 183/30/27l\13/003 TEZ E15®5K— l69/31/281\10/000 PT C E1463GD3K— 159/34/29\20/997 BQ SPL E763GD5F— 125/34/32\17/986 MR E5069/C1D3H 085/55/47—»\12/977 WA C E40636 071/57/53—>\7/973 241930E CV C E10®207l31/25\16/010 AX N E8®®4K—- 196/30/25111/008 TEZ E15635K— 180/31/26l\.8/003 PT C E12®GD4K— l76/33/27\.17——/002 BQ ElOGBGDBF— 139/32/30\.20/990 MR 300D4H 112/49/421\.13/984 WA C SPL 80EB7 088/57/52\.5/978 242030E CV C 17638— 213/32/261\16/013 AX C SPL 12€BGD4K— 203/30/25112/010 TEZ 20695K— 193/31/261\.7/006 PT C 17$4K— 183/33/261\17—/ee4 BX 5GB3F— l63/31/29\.17/995 MR 4OGD7 135/47/36—r\17/991 WA C E8001) 105/57/52—+\.15/983 UNIT 5—THE MOVEMENT OF WEATHER 242130E CV C SP1 300D17_ \\ Radiation from Me warming earl/i 4i F ”$2? \\ warms tbe lower air calls/:19 ’o¢\\ \\ evaporation of lower Part of fa . . “‘V \ 35F mmmmwmmwmmamw was \\\\\. \ l I 3 1 MT 4|.F 44'F ‘ BEFORE NOON-FOG DISSIPATES & \Vé \ Heat radiation from eart/i': war/"in? surface 47F “:43“; if. \ 4. desire]: tbs invenion. F09 evaporates in the c-_~_\\ l \\ I warmed air. 50°F °> \ I \ I 52F " 4L FIGURE 8A.——Radiation fog. fog forms. In strong winds, no radiation fog forms. Excellent condi- tions for radiation fog (clear night skies and light breezes) are fre- quently found near the centers of high pressure areas. This fog is the most common aviation hazard within highs (fig. 8A). A temperature inversion exists when radiation fog develops (see fig. 8A). A layer of air not far from the surface has temperature gradients turned upside down (growing warmer with increase in elevation). Notice that fog develops beneath the inversion layer (fig. 8A). If the inversion layer reaches the ground or very near the ground, as is common on clear calm nights, a shallow “ground” fog develops (fig. 8B). Ground fogs soon evaporate in the warming air of morning, but they hide things while they last. FIGURE 8B.—Ground fog (a shallow radiation fog) develops on clear, cool, calm nights. On nights with temperature inversions, heavy cold air drains into valleys, making fog deepest there (fig. SC). were“ . a“ . ”iii ~FIGURE 8C.——Valley fog is a radiation or clear-night fog that becomes concentrated in valleys because the cold surface air drains into the valleys. Most valley fogs are merely concentrated ground fogs—concen- trated by air drainage, and possibly thickened where a river or lake feeds moisture into the cold air. When deep inversions produce deep fogs in mountain valleys, the fog may not become completely dissipated during the following day. Daytime warming of air near the surface may evaporate the lower fog, “lifting” it to low stratus; but nighttime cooling can again “fog up” .the surface air. _—+ __ m v“ .zab-u‘ g: rev“ =~ ._ - FIGURE 8D.—Fliat spreadingisgkeiis visible evidence of a temperature inversion. ' With smoke in the air, an inversion can be recognized by looking at it. Look at the one in figure 8D. Smoke, like low stratus or fog, spreads at the base of an inversion. Low spreading smoke is itself a nuisance to aviationmand it indicates a probability of fog. When fog forms in a smoky area, the smoke-fog combination becomes intense and persis- tent. It can completely hide cities, and continues even after country fog has fully dissipated. (2) When air blows upslope it cools by expansion,—cools adiabati- cally (just plain “cools,” if that makes you happier). If the air is moist, this causes UPSLOPE FOG (fig. 8E). FIGURE 8E.—Upslope fog can form wherever moist air blows upslope. (3) When warm moist air blows over a colder surface it chills—— and may cool to its dew point, forming ADVECTION FOG. v may get/w FIGURE 8F.—Advection fog is common along many coasts. Advection fog is common along many coasts. It develops when wind blows from warm ocean to cooler land (fig. 8F). You’ll see it at Pensacola or Corpus Christi, and it sometimes extends far inland over cold winter land. It often “lifts” to low stratus during the day, fogging again at night. FIGURE 8G. -——Coastal fogs are common along the west coast: warm ocean;le coastal water; frequent winds from the sea. Along the California-Oregon coast, cold coastal water causes an advection fog (fig. 8G). Where the warm Gulf Stream meets the cold Labrador Current off Newfoundland, and elsewhere where cold and warm waters meet, advection fog frequently covers the sea (fig. 8H) V I r../ // // “/%%FO . FIGURE 8H. —The most persistent sea fog is an advection fog that forms when air blows from warm sea to cold sea. (4) In frontal zones FRONTAL FOGS may form: (a) under frontal surfaces, in cold air through which rain or drizzle falls or has fallen; and (6) along fronts where cold air mixes with (and chills) warm moist air (figs. SI and SJ). Q F06Fok anf‘lbar — FIGURE 81.—-—Warm front fog. UNIT 8—FLIGHT PLANNING FOR FOG AND LOW CEILING WEATHER COLD AIR ———-—D “W MMMJ/ , FIGURE 8J.——Cold front fog. CONDITIONS UNDER WHICH LOW CEILINGS DEVELOP Low ceilings exist under conditions quite similar to the conditions that cause fog: (1) While deep radiation fogs “lift,” low ceilings handicap flight (fig. 8A). (2) Low ceilings exist at the edges of many areas of upslope fog (fig. SE). (3) When warm moist air blows over cold surfaces it may form either fog or low stratus ceilings over large areas. It 1s quite common in winter months for mT air, blowing northward over the East and Middle W'est, to form either fog or low stratus. Fog may exist along the coast and “lift” to low stratus farther inland, or vice versa. Fog may exist during the night and “lift” to low stratus ceiling during the day, or the low stratus condition may continue day and night. In a similar way, sea fog areas may have low ceilings instead of fog. (4) In the cold air under frontal surfaces, low stratus cloud is even more common than fog (see the cross sections shown in this book, figs. 3D, 4A, 9B, 10D, and 10E). Over a broad frontal zone, ceilings may become too low to permit contact flight. In many cases, especi- ally very near the front, low ceilings may prevent even instrument flight. FLIGHT PLANNING PROBLEMS At 0640 EWT, February 23, 1943, you arrived at the operations oflice at NAS Anacostia (Washington, D. C.) to make a flight to LaGuardia Field, New York City. You were qualified for contact flight only. To learn weather conditions at destination and en route. you read the latest sequence report—the report for 0630 (see follow- ing). Studying the report for 0630, answer: Was the weather at Washington contact, instrument, or closed? LG PG WA AZ HT BW XA HX LP LG PG WA AZ HT BW XA HX LP LG PG WA AZ HT BW XA HX LP LG PG WA AZ HT BW XA HX LP LG PG WA AZ HT BW XA HX LP 51 230030E (FEB. 23 0030 EWT) LA GUARDIAN ..Y C. N 0 11/4 K-— 152/48/42/‘3/997 PHILADELPHIA X SPL O 3/4GF-K— 156/40/38—>6/998 WASHINGTON D. C. N O 11/2 K— l59/38/37\2/998 ALBANY N Y. C GD/4GF— 139/32/28T/‘2/992 HARTFORD CONN C O3F-K— 146/31/30T/‘4/995 BOSTON MASS. N 021/2 K— l32/46/27—+/‘6/991 ALLENTOWN PA. 0 2GF—K— 159/34/34C/998 HARRISBURG PA. N 0 11/2 K— 156/40/36C/997 LAKEHURST N. J. 0 3K— 153/43/38—r/‘3/998 230130E N O 11/4K— 152/46/41T /4/997 x O 1/4GF K— 159/36/36/‘5/999 N Oll/ZK— 163/42/400/000 VSBY s I W11/2 E I N 2 C o 3GF— 142/31/28a/2/993 C Q3F— K— 149/32/29T/‘2/996 N Q21/2K— 135/43/271 /'5/992 SPL 03/4 GF— 159/33/320/999 N Oll/ZF—K— 156/38/351‘ \3/997 SPL O 2F— 155/41/4064/998 230230E N 011/4K— 152/47/411/7/997 x Ol/4GF+K— 163/31/31 1/3/000 N Q11/2K— 159/41/3915/999 K ALF C (D/4GF— 1463/30/28 1 3/995 C O3F—K— 149/30/28T3/995 N O2K— 142/41/31T /'5/994 SPL Q3/sGF 159/32/32—.\4/999 SPL N O 11/2F—H—152/37/35C/997 0 11/2 F— 157/38/37—>4/999 230330E N Oll/4F—K— 152/46/41 T 3/997 X O3/8GFK— 163/34/33/‘3/000 N Oll/4K— 159/40/39\.3/999/K ALF VSBY S 3/4 C—69/4GF— 146/31/28 T \3/994 C O3F— K— 149/29/28T 2/995 N O2K— 142/41/29 T /‘3/994 O3/8GF l59/32/32C/999 N Oll/4F— K— 152/35/340/997 Oll/2F— l57/39/38—>/‘/999 23043013 N Oll/4F—K— 152/43/39 T /'6/997 X Ol/IGGF F— 159/32/32—r3/999 N OIF— K— 156/39/37C/998 N SPLdD/ZGF— 142/32/29 T /‘5/993 C O3F— K— 149/29/28T 2/995 N O2K— 146/41/26T /'4/995 X Ol/ZGFK— 149/35/33C/996 Oll/ZF— l55/38/37—r2/999 52 FLYING THE WEATHER 130° 17.5- 120° 115° 110° 105° 100° 95° 90° 85° 80° 75° 10° 65° 60° 5° 50° 45" =’ ‘ ’ «30 ’61 » 1011 :1005 ‘ " « ‘ .éfimbvjw/ 1. as. , /20 A S g 1014 50° 50° 45- w ' 45° 2g/ V , 6 435? 1/5? 1/ a 40' 11,23;1©‘$gg 59 35° _ [V Seag‘xogofi'fl 35° , \ 43111116 { 30° 3°. - UNITED STATES NAVY° February 23, 1943 - 0830 E W 7' 9 250 ‘ L i E; J” 25 ,3 M 115° 110° ' 105- 5'5. MAP NO. 22 230530E LG N Oll/4GF— K— 152/42/39 T /'5/997 PG X Ol/IGGF+F— l56/31/31C/998 WA X Ol/4GF+K— 156/39/39 T /‘2/998 AZ N CD2l/2GF— 146/31/28 T /'5/994 HT‘ C O3F— K— 149/28/27 T 2/995 BW N G)/2K— 146/40/26/‘5/995 XA O38GF 159/30/30/2/999 HX X OOGF+K— 149/33/330/996 LP Oll/2F— l54/39/38—v4/998 230630E LG N 01 l/4GF— K— 152/40/38 T 7/997 PG X Ol/lfiGF+K— 156/31/31 T \2/998 WA X Ol/IGGF+ 156/38/380/998 AZ C SPLCD/3GF— 146/31/26T /'7/994 HT C O3F—K— 152/28/27 T \2/997 BW N CD/2K— 149/40/27—>\3/996 XA SPLOV16GF+ 159/30/3OC/999 HX X SPLOOF+K 152/33/336/‘2/997 LP SPLOl/2GF 150/36/35T f3/997/VSBYSll/2 NW 11/2 The duty officer refused to give you clearance so you studied the sequence reports of the last several hours to find out what was happen- ing to the weather along the route—t0 decide whether you might be permitted to clear later. What has been the barometer tendency since midnight? At WA---’ _____________ ;At PG ________________ ;At LG ____________ What has been the temperature tendency or change since midnight? At WA ________________ ; At PG ________________ ; At LG ________ What has been the dew point tendency since midnight? At WA ____________ ; At PG ______________ ; At LG ________________ What has been the wind tendency (Change in direction and velocity) since midnight? At WA ________________ ; At PG ________________ ; At LG ________________ By this time the forecast had been posted on the bulletin board in the operations office. Can you read it? UNIT 8—FLIGHT PLANNING FOR FOG AND LOW CEILING WEATHER LG 230640E 0630—1430E AWY FCST 2/23/43 NWENG NY NJ DEL MD PA NERN OHIO SRN ONT BJCV PTPG WACV LGWA LGBJ SYNOPSIS WK PRES GRAD WILL CONT WITH HI PRES AREA SERN SXN MOVG SLWLY EWD AND MINN LOW MOVG EWD OVR LKE MICH DURG PRD CLDS AND WEA 0 TO VRBL CIG WILL CONT WITH FOG FRMD ST (1D BLO 400 BY 0700E LCLY SERN SXN DSIPTG BY 0900E VSBYS NEAR 1 OR BLO WITH SMOKE HAZE AND GNDFG IPVG TO 2 TO 4 BY NOON AND LCLY 4 TO 8 THRFTR XCP VSBYS 4 TO 8 IPVG TO OVR 6 BY 1030E NERN NY AND NRN NEWNG TURBC LGT ABV 5000 WRN PA N ERN OHIO AND SRN ONT ICG FRZG LVL AT SFC NRN ME LFTG TO 6500 SERN ME AND 9000 TO 10000 WRN NY AND SRN SXNS WNDS ALF 1000 TO 5000 NERN NY NWENG 270—35 NERN OHIO SRN ONT 220—30 RMN DR 260—25 6000 TO 10000 NERN NY NWENG 270—35 NERN OHIO SRN ONT 230-35 RMNDR 240—20 FTHR OUTLOOK V 1430—2230E NO MATERIAL CHG LG 0 TO CI CD VSBY 1 IPVG TO 2 0830E AND 3 BY 1030E IPVG SLWLY THRFTR TO 4AFTN LGT S—SW PG DNS FOG LFTG TO TH STEB BLO 400 BY 0730E DSIPTG BY 0845E VSBY IPVG TO 11/2 0900E AND 3 BY 1130E AND 4 AFTN 0 TO CI (D AFT FOG LGT VRBL WA VSBY NEAR ZERO WITH DN S GNDFG BCMG DN S FOR WITH ZERO CIG BY 0700E. IPVMT AFT 0830E BCMGG WITH VSBY 1/2 BY 0930E. VSBY 2 BY 1100E AND 3 00 MORE BY 1230E. LGT SFC WNDS Weather conditions shown on Map No. 22 (0830 EWT, Feb. 23, 1943) Station Ceiling - Clouds (amount and types) Visibility Present weather ature point Barometer tendency Wind (direction and velocity) Pressure New York _______________________________________________________________ Philadelphia _____________________________________________________________ Harrisburg _______________________________________________________________ Boston __________________________________________________________________ Albany __________________________________________________________________ Washington ______________________________________________________________ 53 KX CI (D. VSBY 1 BCMG 1/2 AT 0730E 1 AT 1000E AND 3 OR MORE BY 1200E LCL SMOKE AND GNDFG LMTG. LGT SFC WNDS BCMG SSW 10 MPH AFTN NA CI (D. VSBY 3 BCMG 5 OR MORE BY 1000E LCL SMOKE LMTG. LGT BCMG SSW 15 MPH AFT 1000E On the basis of these reports and forecasts you decided that you would wait and see what the weather map for 0830 EWT looked like. When the weather map was completed (see Map No. 22), what conditions did it show? (Answer on the blank at the bottom of this page.) What is the cause of the fog over much of eastern United States? According to the 0630 forecast, at what hour would you expect to be permitted to clear from Washington for a contact flight over Philadelphia to New York? __________________ What Weather change, enabling you to clear, did the forecaster expect? _____________________________________________________ At what time were you actually able to get clearance for contact flight from Washington to New York? (Answer after studying the accompanying airway sequence reports for 0730 to 1430) ........... What was the Washington weather at that time? ceiling _________ visibility ____________ Philadelphia weather: ceiling _______________ visibility ____________ New York weather: ceiling _______________ visibility ____-______T,_ What alternate terminal did you select? __________________ What was the weather at your alternate? ceiling ______________________ visibility _________________ 230730E LG X 0 3/4 GF—K— 152/39/380/997 PG X SPL OOF+K— 156/30/30\.4/998 WA X 0 1/2 GF 156/38/37C/998/VSBY N 11/2 AZ N SPL Q)/2GF— 146/33/28T6/994 HT N SPL —(D/2F—K— 156/28/27T‘\2/998 BW X SPL ®3/4K— 152/41/28—i\.5/997 XA SPL O OGF+ 159/30/300/999 HX X 00 F+K— 156/33/330/998 LP 0 1/2 GF 163/35/35T2/800 230830E LG X 0 1/2 GF K— 166/38/36'\5/001 PG X 00 F+K— 166/31/310/001 WA X C) 1/2 GF 163/38/360/000/K ALF AZ N GD/2l/2GF— 146/33/28T1/994 HT N —(D/ll/2F—K— 163/28/27T'\2/999 BW X (D/3/4K— 156/40/2813/998 XA SPL OOF-l- 173/30/301/2/002 HX X OOF+K— l59/33/33T2/998 LP O 1/2GF 165/35/35->3/001 54 230930E LG X C 5/16 KGF— 166/40/37T3/001 PG X OOGF+K— 166/32/32—i3/001 WA X —63/ 1/2GF l66/39/37C/001 AZ C SPL —<1D/3HK— 146/36/30T'\9/994 HT N —CD/11/2K—H 163/31/3011/000 BW X —(D/3/4K—— 163/39/29T7/000 XA OOF+ 176/31/31 1/2/003 HX X OOF+K— 159/34/34‘\2/998 LP SPL —®/1GF— 170/38/330/003 231030E LG X —(D/5/16 KGF— l66/46/40"\3/001 PG -X SPL —(]D/3/4GF—K— 163/43/41 T'\4/000 WA X —\4/995 HX N GD/ll/2K— 129/58/4417/989 LP —(D/5 H 145/64/38T\12/996 231430E LG C -0D/30®5K- 132/58/41T 17/991 PG C —(]D/3K-—H 132/62/44 T /'13/991 WA C —(D/6K— 129/68/49T 17/990 AZ C —GD/4HK— 105/53/381'\l6/982 HT N —(D/2l/2 K—H 132/60/46/‘15/992 BW C (D/4K— 129/63/501/17/990 XA ~—(D/11/2HK—— 129/62/471/‘13/989 HX C (ID/3K— ll5/67/57T/‘21+/986 LP —(D/6H 134/67/37T'\17/992 FLYING THE WEATHER Winds aloft 2/23 LG15 01906 2022 22024 2126 42327 2222 PG16 01904 1916 22022 2222 42322 2322 WA15 01907 1812 22119 2220 42228 2125 62126 2322 82421 2426 02528 C815 01205 1424 21322 1416 41414 1514 61513 1417 AG16 01004 21703 1511 41514 1612 61611 1616 81616 1710 01302 1103 21002 2602 42704 3007 03309 0015 01405 2214 22434 2446 42450 2452 62452 2456 0016 01918 22340 2444 42418 2456 62455 2464 FW15 02116 22440 2542 42442 2347 62261 HX16 01005 1914 22126 2234 42232 PT15 01915 22232 2346 42342 2340 62338 2338 82339 2446 02441 N016 00105 1414 21615 1915 42210 2408 62708 2710 82810 3014 02915 2813 22915 2921 42923 2824 03141 Flying contact, you could not fly higher than 3,500 feet above the surface. Consulting the winds aloft report (printed on this page), what did you decide was the best elevation that day for contract flight from Washington to New York? (The true course from Washington to New York is 51°. ‘z‘rfifiza’k Lieutenant “Columbo” Smith wrote you that on February 23 he expected to fly from Eureka, Calif. for New York, stopping at Chicago for fuel. “ Columbo” flies instrument! Could he clear from Eureka at the time of the map (Map N o. 22)? ________ Could be clearfor Chicago at that time? _ _ _ _ _ _ _ _ _ _ What was the general weather situation between Eureka, California and Chicago? _________________________________________________ What was the general weather situation between Chicago and New York? __________________________________________________ NOTES it 72? it PILOTS’ COMMENTS “I remember one particular occasion when this (drifting) fog rolled in but the wind was practically calm. We could see the solid wall of fog approaching slowly. It hovered above 100 feet from the remote control p for fully 15 minutes, not moving at all. The whole time the front of, this mass was clear and distinctly a shear straight wall. We could not see more than 75 feet into the fog, yet to the north it was perfectly clear. a It finally moved over the 'field and blotted out the whole valley before morning.” “I used to work for the United States Coast and Geodetic Survey in Alaska in connection with geodetic work in the Talkeetna Mountains and the Alaska Range, * * * you could see that it was the same air which, when blown up along the mountain side, would make fog at a certain elevation as fast as it arrived there and that in blowing down on the other side in reaching a certain place, would suddenly absorb back its water particles and become clear again. I used to wonder how such a strong wind could become foggy and then suddenly become clear again.” ../°' / //// / 942m?" ‘ 031.4 - 0“ /// / fig: ,2???» l 10 :54 +4” M50 .T 74 300 MILES 24 ‘ 2 .7 If 73 1'10/ WW 4%,? \ , _ / ' 180 ‘71 207 8311i!) Weflberlglfll *fiw 74%“ air/mom g 36“» s: ° V‘ i / I230 1637 ,6" a t, MAP N0. 23 The area of cloudiness shown on the map of 1230 CST, September 19, 1941, results from the cool polar continental air underrunning the warm, moist tropical maritime air. The tropical air, ascending over the slanting frontal surface of the polar air, cools and clouds up. Rain or drizzle falls from these clouds above the frontal surface. Notice the thick alto-stratus over Kansas City and over Albuquerque. Throughout much of the cloud and precipitation area, however, the middle clouds cannot be observed from the surface, for low clouds obstruct the view. These low clouds are the stratus that form in cold air beneath frontal surfaces when precipitation from higher clouds brings the cold air to its dew point. From 'the standpoint of the flyer, these low clouds do the mischief. Notice that in Map N o. 23 they produce low ceiling over a broad area. UNIT 8—FLIGHT PLANNING FOR FOG AND LOW CEILING WEATHER At 1230 CST, September 19, 1941, you were at Omaha preparing to take off for El Paso, Tex. You had an instrument rating. The direct route from Omaha to El Paso would cross mountains southwest of Roswell, N. Mex. (see fig. 1F). What weather conditions at Roswell caused you to decide not to fly this direct route? _____________________________________________ What conditions would you probably have encountered in the mountains southwest of Roswell? _______________________________ Did weather conditions permit you to clear from Omaha to fly a course via Dodge City, Amarillo and Lubbock to Wink and then If not, what made it impossible? ___________________________________________ westward to El Paso? ___________________________ What and where was the lowest ceiling along this proposed course? The lowest visibility? ____________ To what extent and in what way might you expect this weather to change within the next few hours? ______________________________ If possible to make an instrument flight from Omaha to El Paso (along any course), draw up your flight plan. Follow this outline: FLIGHT PLAN: Classification of flight: Course: Altitude: Alternate terminal: 55 flirt“! That cadet now sitting next to you was in Omaha with you at 1230 CST on September 19, 1941. He, also, wanted to fly to El Paso, but didn’t have his instrument rating. Was it possible for him, flying contact, to clear from Omaha for El Paso (any course)? If not, what made it impossible? _______ $37 $17 7% NOTES \\\\\\ \\\\\\ \\\\\ \\ \\\\ 56 FIGURE 9A.—A cumulo-nimbus cloud. FLYING THE WEATHER UNIT 9 FLIGHT PLANNING FOR THUNDERSTORM WEATHER THUNDERSTORM HAZARDS A thunderstorm might be all of the major weather flying hazards rolled into one! Turbulence is excessive within the storm, beneath it and around it. Vertical air currents within the storm may exceed 200 m. p. h. and great eddies whirl between the opposing up and down currents. In such atmospheric turmoil a plane can be lifted or dropped great dis- tances, and often may be thrown completely out of control. Area of maximum turbulence and gustiness: the lower front portion of the storm. Icing conditions occur in all thunderstorms, for all cumulo-nimbus clouds (thunderheads) extend to above the freezing level.‘ The flat anril top of a cumulo-nimbus is composed of ice-crystal cirrus, so presents no icing danger, but somewhere beneath the anvil the cloud becomes water cloud. In water clouds with temperatures of —20° to 0° C. (0° to 32° F.) ice forms on any plane that enters. W'ater drops in cumulo-nimbus must. grow large before they can fall through the up-draft; and at temperatures of —10° to 0° C. (15° to 32° F.) large drops produce glaze, the worst type of ice. The icing hazard is not serious in summer thunderstorms, but at other seasons icing may extend to or near the surface. Hail large enough to inflict severe damage is present in many thunderstorms—even when no hail reaches the ground. It is most often encountered around the edges of a storm, and many pilots con- sider it even more dangerous than the extreme turbulence. Milky— white or greenish color under or around a thunderstorm may mean hail-fly clear! Lightning may blind a pilot long enough to cause him to lose control of the plane. lr’isibility is reduced by heavy precipitation under thunderstorm clouds. Also, the clouds may hide mountain sides or summits. HOW THUNDERSTORMS LOOK Like wild boars and copperheads, thunderstorms should be recog- nized. The cumulo-nimbus cloud cloaks the storm—makes it visible. No two cumulo—nimbus look exactly alike—but a pilot who knows the basic cumulo-nimbus characteristics (and every PILOT knows them!) will recognize a thunderstorm when he approaches one (see . fig. 9A). The cumulo-nimbus has five basic characteristics:_ (1) Like all cumulus clouds, it has “wool-pack” or “cauliflowerm‘ form; but the full-developed cumulo—nimbus shows this only on its sides. (2) An anvil top, made of icy cirrus, crowns the storm—cloud like a flat-topped umbrella. It generally extends far forward in the direction the storm is moving. Air is smooth above the spreading anvil for the anvil is formed where air currents cease rising and spread outward. (3) A roll cloud billows forward along the lower front edge of the great storm cloud. Never get in this roll cloud and never get near it! l Exception: In the tropics not all cumulonimbus clouds extend to above the freezing level. Turbulence is excessive, and strong gusts blow forward from the ad- vancing storm—they come out under the cloud and keep it rolling. (4) A dark area, within the cloud and near its base, is the core of the storm, and the portion with heaviest rainfall. Every thick cumulus cloud has a shaded dark bottom; but that of the cumulo- nimbus is threateningly black. (5) Lightning is a great help in recognizing a thunderstorm, espe- cially at night. Moderate thunderstorms, and the back parts of many storms, have horizontal lightning streaks; but vertical streaks flash .through the dangerous front portions of severe storms. SPECIAL Nora—Direction of movement of a thunderstorm may be judged by observing (1) the roll cloud, (2) the anvil top, and (3) cloud shelves (fig. 9A). The roll cloud develops only on the front edge of thunderstorm clouds; the anvil and “shelves” protrude farthest in front of the storm. WARNING.——You seldom see all characteristics of a cumulo-nimbus cloud. For example, when you fly high the roll cloud may be hidden from your view by cloud “shelves” that may extend forward from the ' storm cloud; and when you fly low the anvil may be difficult to see or recognize. CONDITIONS UNDER WHICH THUNDERSTORMS DEVELOP In addition to recognizing thunderstorms “at sight,” a pilot should know the different weather and terrain conditions that cause thunder- storms; this enables him to know (after study of the current weather map, weather reports and forecast) where to anticipate thunderstorms on any particular flight, what kind to anticipate, and how to avoid flying through one. Thunderstorms develop wherever moist warm air ascends in large quantities! Air mass thunderstorms, common in Our warmer seasons and in the tropics, develop when moist air is heated by the surface over which it moves. Strong updrafts start over the warm surface—like the up- drafts over a stove or bonfire. As the ascending moist air cools to its dew-point, cumulus clouds form. Condensation of moisture releases heat of condensation, and this released heat stimulates still stronger vertical currents. Soon a thunderstorm rages. Over land, air mass thunderstorms are most frequent on hot after- noons; over tropical seas, they are most frequent at night. Air mass thunderstorms generally develop miles apart, in scattered haphazard pattern. You can fly around them-and certainly should! Mountain thunderstorms are a special type of air mass thunder- storms. They develop when moist warm air moves up a mountain slope. When “mountain climbing” air cools to its dew point, it may release sufficient heat of condensation to cause great instability and breed a thunderstorm. Mountain thunderstorms can be very severe and may extend to great heights. They may be isolated, like ordinary air mass thunderstorms, or may form a continuous impassable line along a mountain range. - Frontal thunderstorms, both warm front and cold front variety, form whenever the warm air that ascends along the front is sufficiently warm and sufficiently moist. Warm front thunderstorms are scattered ahead of the warm front—— can generally be flown around. Cold front thunderstorms may be scattered back of the cold front, of type similar to the warm front variety and easily flown around. UNIT 9—FLIGHT PLANNING FOR THUNDERSTORM WEATHER Map N o. 24 illustrates this type of cold front thunderstorms. A cold front that is fast-moving and steep, however, may have “squall line” thunderstorms—severe storms that may occur in an almost continuous line just preceding the cold front, as shown on Map No. 25 and fig. 9B. A flight mission must be extremely urgent to prompt even the most experienced pilot to fly through a squall line. Cadets simply don’t do it! WHERE TO FLY . In solving the flight planning problems in this unit on FLIGHT PLANNING for THUNDERSTORM WEATHER, follow these rules: (1) If possible, fly around a thunderstorm or a line of them. (2) If impossible to fly around, find a place to land—sit down and wait. (In some cases this may mean going back to the home field to wait for better flying weather.) You should not, at this stage in your flying career, consider flying over or under a thunderstorm; and, obviously, you must not consider going through. Experienced pilots on urgent mission, when they can- not go around, take one of the following courses, presented here in order of preference: (a) go over, (b) fly through a saddle—a high break between two storm clouds, (c) “hedge hop” under the storm, or (d) go through—but go through on a course at right angles to the front, so that you will get through in the shortest possible time. FLIGHT PLANNING PROBLEMS At 0330 EWT, August 3, 1942 you departed from Philadelphia, Pa., with important cargo. It was necessary that the cargo be delivered at Columbus, Ohio; St. Louis, Mo.; and Kansas City, Mo. Having studied the weather map of 0230 EWT (Map No. 24), you knew weather conditions between Philadelphia and Columbus to be as follows: General: Overcast to broken clouds at Pittsburgh becoming over- cast again at Columbus. Scattered light to moderate thunderstorms east and south of Pittsburgh. Ceiling: Unlimited except in thunderstorms. Only high and middle clouds except at Columbus, which reports low cloud, strato—cumulus. Visibility: Nine miles except at Columbus where smoke restricts visibility to 4 miles. Surface winds: West 4 to 7 m. p. h. becoming calm near Columbus. You were cleared for Columbus upon presentation of the following flight plan: FLIGHT PLAN: Classification of flight: Contact. Course: Philadelphia-Pittsburgh-Columbus. If any thunder- storms are encountered, will go around them to the north. Altitude: 4,500 feet MSL over mountains, then 2,500 feet (west- bound planes must maintain altitudes on even thousand feet levels plus 500 feet. Low elevation selected for this flight because head winds from west will increase in velocity with increase in altitude.) Alternate terminal: Fort Wayne (Selected because it is clear and has excellent visibility.) You arrived at Columbus at 0700 EWT and were ready to take-off for St. Louis at 0830 when the station received the following sequence reports: 57 030830E COLUMBUS (D/(1D3K— 166/71/6713/002 BRM RSG SLWLY DAYTON E50693GDF— 170/70/691\.5/003 BRM RSG SLWLY INDIANAPOLIS 50$11/2K— 166/72/7ll\.3/002 BRM RSG LGT TSTM PASSES MVG SEWD EVANSVILLE E5OGD 166/76/71/5/002 BRM RSG CHICAGO 7OGD6H— 176/65/570/005 BRM RSG SLWLY SPRINGFIELD ILL. 30636H— 173/72/691\.5/004 BRM RSG SLWLY ST LOUIS MO. E40$6T—F——R—- 183/73/72—»/‘3/007 BRM RSG SLWLY ADVANCE MO. ®6H~ 152/76/74110/998 BRM RSG SLWLY SPRINGFIELD MO. E30$6T—R—F— 166/71/709/5/002 BRM RSG SLWLY COLUMBIA MO. 500D6H— 176/67/65\.5/005 BRM FALLING KIRKSVILLE MO. 0 149/51/46 T/3/996 KANSAS CITY MO. 30$6R— 186/67/661/4/008 TSTM PASSES MVG SEWD According to the 0230 E map and the 0830 E sequence reports, what were the 0830 E weather conditions between Columbus and St. Louis? General: Ceiling: 58 FLYING THE WEATHER 45°; , Z, 54 ‘1," ,, M. .. 6 .2, g / Max-*«oggye' a 68 ‘°° 69 173 Men 6: W APOLIS)‘, ' 6142 L, 2 ’/ as“ *7 35° ,: / 14 //////5Q$ - / 7 .T [70%, 5 // 5; . OKLAHOMA CITY 129 76 66<§$4¥ 70 f 5 : 30' ,, g 82 2r v :39 as“? 58 / + M “7% 705‘ ~umfei) STATES NAVY- Aagusf 3, 1.942 - 0230 EWT ; \ 25" ,, SCALE ,_ ,, h H . (I 300 names “E, ,, a 120' 113° 110° 6 5 105° 100° Visibility: Surface wind: Make your flight plan: _ FLIGHT PLAN: Classification of flight: Course: Altitude: Alternate terminal (and why chosen): At 0855 CWT (notice change in time zones), when you had reached a point about half way between Columbus and St. Louis, you requested a special weather report from St. Louis. You received this report in code and decoded it as follows: 0855 C St. Louis; special; ceiling 200 ft.; visibility 1 mile; wind southwest 22 gusty. Heavy thunderstorm in progress. What is your procedure? _____________________________________ Following are the sequence reports for this area for 0830 C to 1230 _C. According to these sequence reports, at what hour were you able to land at St. Louis? _______________________________________ 0830C INDIANAPOLIS 40$2K— 168/72/70\.4/003 EVANSVILLE 40696K— 168/76/72/5/003 CHICAGO 850D7K— 176/67/57C/005 SPRINGFIELD ILL. 40636H— 174/72/69\5/004 LTNG IN SW ST. LOUIS MO. 5€B3TF—R—— 176/73/72 T 3/005 TSTM INCRSNG IN INTNSTY ' ADVANCE MO. 70$4H— 152/77/75/8/998 SPRINGFIELD MO. 15633T—F—R— l68/72/70‘\5/003 COLUMBIA MO. 500D6H— l76/66/64\.6/006 LTNG IN NE KIRKSVILLE MO. (1)150/52/47/‘3/997 LTNG IN SE KANSAS CITY MO. 7OGD8R— 190/63/59\.5/009 CLRNG C(‘éIECNORDIA KAN. 20$2K— 183/68/57«—3/997 TSTM PASSES MVG D WICHITA KAN. 500D 156/70/684—12/999 TSTM SE DODGE CITY KAN. 50$2F— 152/66/66/8/998 OKLAHOMA CITY (1D9R— 139/76/67T'\4/996 TSTM NW AMARILLO 30$6T l43/77/69t—{9/995 UNIT 9—FLIGHT PLANNING FOR THUNDERSTORM WEATHER 0930C INDIANAPOLIS 6OQD4K—170/71/67—»4/003 EVANSVILLE 25$4K—166/77/75k6/002 CHICAGO O7K—176/67/56\2/005 SPRINGFIELD ILL. 5OGD6K— 175/73/6864/005 LTNG IN SW ST. LOUIS 3$11/2T+F—R+ 166/68/68—vl4/002 ADVANCE 65634H—154/78/75/5/998 SPRINGFIELD MO. 250D8R— 171/70/68\.8/003 COLUMBIA MO. 60®6H~ 177/68/63\.3/006 KIRKSVILLE (1)151/54/49/‘3/998 KANSAS CITY 750D 192/63/56\.5/000 CONCORDIA 350D5K—185/69/59/‘4/007 WICHITA 500D157/71/684—10/999 DODGE CITY 49$2F— 152/66/664—7/998 OKLAHOMA CITY l8®4T—F—R— 132/71/699/14/992 AMARILLO 650D9R—146/74/65—fl/995 1030C INDIANAPOLIS CDSH—K— 172/75/68—>3/003 EVANSVILLE 15€B3T——R— 162/74/72'\8/001 CHICAGO 0 7K- 177/68/57\.5/006 SPRINGFIELD ILL. 65GD5K— 176/74/67\5/005 ST. LOUIS MO. 30$4R— l71/68/63\8/003 TSTM PASSES MVG SEWD ADVANCE 50$3F—H— 155/81/79i—7/998 SPRINGFIELD MO. lOéBST—R— 169/67/66\4/003 COLUMBIA 25$4H—K—— 169/73/6964/002 KIRKSVILLE (1D9H— 174/62/57—>5/005 KANSAS CITY (11) 187/68/65/‘8/009 CONCORDIA 30(]D5K— 186/69/64\.5/008 WICHITA 35QD8H— 162/73/68<—-/8/000 DODGE CITY 45634F— l55/74/71e—6/998 OKLAHOMA CITY 25$6R— l34/78/74'\12/994 AMARILLO (D 156/75/64/‘4/999 1130C INDIANAPOLIS G6H— 166/78/67—v4/002 EVANSVILLE E5OGD6R— 160/82/71/‘6/000 CHICAGO O 179/69/57\.4/007 SPRINGFIELD, ILL. E8OQD8 184/74/64\3/008 ST. LOUIS 55$7R— 169/72/63\.5/003 ADVANCE 70635H— 154/85/77T6/999 SPRINGFIELD, MO. 50$5H— 166/74/66—v4/002 COLUMBIA 70696K— 165/78/70/‘5/002 KIRKSVILLE (ID7H— 182/70/59—>9/006 KANSAS CITY 6®21/2T+F—R+ 175/70/7014/002 CONCORDIA 2595K 183/74/6715/005 WICHITA 25637H- 168/78/68/6/002 DODGE CITY 70®4F— 155/77/7498/998 OKLAHOMA CITY 500D8H— 136/82/72‘\10/993 AMARILLO O 159/76/62 T 4/999 1230C INDIANAPOLIS (Den— 163/83/66—>/‘6/002 EVANSVILLE a) I56/90/7o\.3/999 CHICAGO 0183/74/58\14/008 SPRINGFIELD ILL. <11) 193/77/58—i5/014 ST. LOUIS cu) 162/79/63\.4/000 ADVANCE 63152/90/70—>3/998 SPRINGFIELD MO. CD 163/78/68/‘6/002 COLUMBIA 12(D5T—-R— 159/75/72/4/999 KIRKSVILLE esn— 196/75/60/12/012 KANSAS CITY 2OGD7R— 173/70/68/6/002 TSTM PASSES MVG SEWD CONCORDIA 20$190/73/69e—{5/008 WICHITA zoeaen- 176/79/67'\4/006 DODGE CITY 01) 156/83/57‘\14/997 OKLAHOMA CITY (D 139/94/68'\10/996 AMARILLO o 163/78/60'\2/000 59 Assuming that one hour was required at St. Louis for refueling, etc., when was the weather satisfactory (according to the sequence reports) for clearance to Kansas City? __________________ At the time you leave St. Louis for Kansas City what is the weather situation between St. Louis and Kansas City? General: Ceiling: Visibility: Surface Wind: Draw up your flight plan: FLIGHT PLAN: Classification of flight: Course: Altitude: Alternate terminal (and why chosen): 60 At various stations throughout the country pilots reported for flight duty at 0230 EWT, November 10, 1942. With a glance at the weather map of 0230 E (Map No. 25) you see one outstanding feature. What is that impressive feature? _____________________________________ Why is it important to pilots? __________________________________ (See “Conditions under which Thunderstorms Develop—Frontal Thunderstorms,” p. 57.) When a weather map like this (except for temperature) appears in late spring or early summer, what kind of storms may occur in the southern and plains states? ______________ When planning flights for the morning of November 10, 1942, it was necessary to consider the probable movement of the storm center and fronts. A glance at the map drawn 6 hours previous to the 0230 E map revealed that the depression center had moved northeastward. By extrapolation the aerologist determined that the center would continue moving northeastward, reaching by 0830 E a point near Haileybury (as indicated on Map N o. 25). The aerologist estimated that by 0830 E the cold front would have moved so that it would extend from the south end of the occluded front through Cleveland: Pikeville, Ky.; Knoxville; Birmingham; and Navasota, Tex. Draw in the extrapolated cold front._ The aerologist estimated that bv 0830 E the warm front would ex- tend from the occlusion through Montreal and Syracuse, east of Kylertown and west of Washington. Draw in the extrapolated warm front. You are to draw flight plans for the morning of November 10, 1942. In doing so you should know that when weather does not permit continuous flight from point of take-off to desired destination you may (I) wait until weather improves or (2) clear for a specifi ed point along your route where you will land and wait until weather permits you to clear for the desired destination. On a long flight, if weather were satisfactory over the entire route, a Navy pilot would probably land and refuel every 500 to 1,000 miles. All flights on the morning of November 10, 1942, were scheduled to start at 0300 EWT and the planes used on all flights had a cruising speed of 200 mph. Consulting the 0230 E map, considering the extrapolated movement of the weather, and consulting the wind aloft chart for 0500 GCT draw flight plans for the following flights: FLIGHT A: Boston to Seattle via Albany, Buffalo, Chicago (Joliet) St. Paul and Billings. FLIGHT PLAN: Classification of flight (contact or instrument): ____________ Procedure (Include here a statement of any variations from a normal flight plan; that is, any variations from a plan to clear at 0300 E and proceed to planned destination with normal refueling stops): ________________________________________ FLYING THE WEATHER Altitudes (select level or levels with most favorable winds. Do this for entire route. This may be one level for the entire route or different levels for different sections of the route): Alternate Terminal (Select an alternate for only the first planned stop. Explain your choice): _____________________________ FLIGHT B: Washington to Dallas via Nashville. FLIGHT PLAN (For this and remaining flight plans relative to MAP No. 25, follow instructions given for planning FLIGHT A): Classification of flight: Procedure : Altitudes: Alternate terminal: FLIGHT 0: Jacksonville to Chicago. FLIGHT PLAN: Classification of flight: Procedure : Altitudes: Alternate terminal: FLIGHT D: Chicago to Jacksonville. FLIGHT PLAN: Classification of flight: Procedure: Altitudes: Alternate terminal: FLIGHT E: Mobile to Washington. FLIGHT PLAN: Classification of flight: Procedure: Altitudes: Alternate terminal: 350005—- '\' I g —- 30,000 — ~ :J J N fl) 100m: ’ 25000’—— liar/z 25000, 5 C A L E I 20,000’— ALTO -cumu LUS CIR R u 3 ——20,000 w/rh ALTO-STRATUS ——3 / -- .. c- “é o . I5,000’—- 53% V___ ~ ALTO-CUMULUS élf’i--—— ———75,000’ . , C01 w/rfi ALTO-STRATQ§/”'_#, 0 AW 0 FRO/V7- \ 6 «4—5; 4;}..- m 40° fr?“ \-__-;%;_gfl@® f” ‘ ;~— , /___ALTO' ’—-—-‘" \‘\ _m“w%f‘“—’* FRO/V7 —-—70,000 ’0’000 cumuugr/ \\ —; Gym? WARM :gr’égg53% STRATUS \\\‘\\\ 17*»’-—~. STRAJUS I ‘Q 6"? ' T" _ o ,/’~———v— T, . 55‘ A \ V—._?___-__ I 5,000 a; 0- ._ V; \1-‘ __ {QC/— - ,. v _ -. STELJUS \-0?: JV.” 5,000 ~-._'- \- \\ _J"J‘ ~ \ *— FOG 32 34 t£240 32—4261 14 274 20 240 49K.020 55 936 59 06034 456088 456 29 254 4‘3“” 123/ 4:: 333/ @+2/ —4\ \—O+2/‘ Ei—ZO/ 31 I +26 {7 +38 . -2s 4 ~40\ :7 -37\ +34 4—.— —16 39 3 v 26 if 13 15 23 v 45 v R 56 V 9. 42 35V 14 14 75 26 SEATTLE SPOKANE GREAT BILLINGS BISMARCK FARGO ST. PAUL JOL|ET WILLOW BUFFALO ALBANY PORTLAND, FALLS RUN SYRACUSE ME. FIGURE 9B.—Cross-section (Pacific to Atlantic) showing "squall line” over Middle West, November 10, 1942. 120° 115° 110° 105' 100° 95° 90° 85° 80’ 75° 70° 65’ 30’ 45' Q 35° 25° *mx- “ 1033, 1020 177 //l 4- ‘ 1/ {17 4’ ‘3. 32%: A 35" ° UNITED STATES NAW° November IO, 1942 - 0230 [WT 90m “W , ( 300 Minzsg‘ g - X \ >30° N 25° " 2 i 30,000’— —— 30,000’ 25," 000 '— 25:000’ 20,ooo’— ALTO~CUMULUS CIRRUS w/fh ALTO *STRATUS —-3 ——-20,000 ’ 15,000 '— O ALTO-CUMULUS ~l?.f.-.— —75,ooo" mm ALTO-STRATQ§/ ’ «(gs—3» ' as W A R M FRO/V7 ——70,000’ , a» ~ 4 ‘ // §_T_§A'rus, , . .. t. " ' STRATUS __ ”igl—‘/ —“==—- ‘_ .. ,. ,1 \ 0 VET—é—SOOO’ \‘ b \‘ 3w \ w— FOG .3 41 w 32 32 339 34 6 240 32 261 14 274 zoéacyo 1 59 6034 456058 456 29 254 43<9> + / 3: +6/ 6©+2J§VO-4\ \——o+2/‘ 3 2 . ° 40 -40\ 6 -37’\ +34 4:: —16 I3 15 23 56 34 35 1X 46 12; K if 5/. 42> 715;) \go SEATTLE SPOKANE Exit; BILLINGS BISMARCK FARGO ST. PAUL JOLIET WkLbflW BUFFALO FIGURE 9B.——Cross-section (Pacific to Atlantic) showing "squall line” over Middle West, November 10, 1942. ALBANY PORTLAND, SYRACUSE ME. 1023. 1020 _ 1017 1014' / 10“ //x / , ‘ , ' +203. 45‘ 35‘ g 30’ .N\ M \- n 73“?“ E9043; 1125.420: My 1 ‘ \\\\\ 69 ) ~: 3 M M : , y \ :~ 5 , 4 i M: ‘M 11 X. M I8 b T‘ M - M \ 9 M é ‘ - \\ 13?; fl 4 \* \ y :M x M wk a ‘\ 2:11:14]. ta 15 0‘— 8 4° gafl , 2 M ’ 65: ,, V NAVégA 2 M I V 1‘ , h ,M . (2?:fi14f 3355353 wigs, , v; '3’ 44 n, 1 6 79g/‘%95g‘4 ‘ ,Myxg : 7 ’ ' UNITED STATES NAW° 1° , ' Novemberlo, 1942 - 0230 m7 \ 25° J, 2pm” \M , , f K“ a 4M" ’ , 2 My ‘3. _ j ' SCALE ”W *‘f ’ ‘ ‘ 7° ’ . soc was y ‘ \fo; , M t ./ 9M, w M V % W WW . ‘ { M w -: In A 115; 1tx0' 105' 1oo- 95° 90° 85° 80° O — 524786 (Face p. 60) MAP N0. 25 61 UNIT 9—FLIGHT PLANNING FOR THUNDERSTORM WEATHER an m 1a. D m m m w .w n fl m d kin MNo JA.,n ..Lw FPHJ TTw um FF Procedure .' Altitudes: Alternate terminal: FLIGHT 0: Washington to Mobile. Classification of flight: FLIGHT PLAN: Procedure : Altitudes: Alternate terminal: FLIGHT H: Dallas to Washington. m .W fl. only mm Lm PM Ts “Hm I L F Procedure : 110° 2,000é 710° FIGURE 9C.—Winds aloft chart, November 10, 194-2. 62 Altitudes: Alternate terminal: FLIGHT I: Seattle to Oakland. FLIGHT PLAN: Classification of flight: Procedure: Altitudes: Alternate terminal: FLIGHT J: Seattle to Spokane. FLIGHT PLAN: Classification of flight: Procedure: Altitudes: Alternate terminals: FLYING THE WEATHER NOTES NOTES UNIT 9—FLIGHT PLANNING FOR THUNDERSTORM WEATHER PILOTS’ COMMENTS "We had a ship struck by lightning the other day. It occurred in a squall just south of Castlerock, Wash. It didn’t do any damage other than to scare hell out of the boys and the stewardess. (There were no passengers.) On the wing tips and on the fork of the tail wheel and on the tail wheel hub there are spots that show burns. There was also a flash that momentarily blinded the pilots. It did not effect the radio operation as they called in shortly after it happened.” ‘ —Portland "I remember several severe hail storms in Iowa, approximately 1924, I925, 1926; these occurred south-southwest of Iowa City about 30 miles, which is now just a little south of the Moline—Des Moines Air Line. Without exaggeration one of these storms had hail 4 inches in diameter. This storm occurred in the early morning hours on the 28th of June, but I cannot remember the year or the dates of the other storms.” —Des Moines "Have seen hail in Fort Worth, Tex., the size of golf balls, this storm came in as the plane was landing, we were able to get this plane inside. I know that it would be impossible for any aircraft to withstand this storm as, it lasted nearly 20 minutes, this was approximately 4 p. m. in the afternoon.” —Des Moines "I was interested and surprised to hear some of the pilots flying between Cheyenne and Salt Lake City state that they would rarely consider flying beneath a thundrestorm but would usually fly over or through the top. These pilots in turn were surprised when I told them that east end pilots usually chose to fly under rather than over or through the top.” —Chicago "Have heard a few pilots and copilots make the statement that they have never seen a thunderstorm so rough that they could not fly instru- ments in them. Would like to suggest that I do not think they have seen them quite all yet, but if they keep on looking they probably will find at least one.” 2d Pilot—Cheyenne "While flying blind in overcast in the vicinity of Sunbury, Pa., in a 247 at 10,000 feet we hit a down draft and fell 4,000 feet absolutely out of control. I think we were inverted more or less—anyway, the gyro-com- pass and horizon went out like a candle in a tornado. At about 6,000 feet we regained control for about 15 or so seconds and then hit another draft almost as violent as the first. We regained control from this one about 3,000, and as the hills in that vicinity are about 2,000 feet we decided that the passengers would be more comfortable on a train and we pro- ceeded to land at Sunbury. There was no squall line and this storm must have been of the overrunning type as there was a solid overcast at about 3,000 feet above sea level. _ Another trip that preceded us only 45 minutes experienced only moderately rough air. This occurred at about 6:00 a. m., June 1933.” . 2d Pilot—Chicago "On another occasion, (and it was just at daylight too) one of the boys flew into an innocent looking thunderstorm near Sunbury, Pa. He isn’t entirely clear as to just what did happen during the next few minutes, but he vows that it finally turned him loose upside down. He regained control with precious little altitude to spare, landed at Sunbury and cancelled the trip.” 2d Pilot—Chicago "I once saw a . . . . of . . . . Air Lines come into Newark from ...... with every seat, in which a passenger had been strapped, pulled loose from the floor. Those passengers were in sad shape.” 2d Pilot——Chicago "Last summer one of our ships attempted to (and did) get through a line squall near Toledo. They took an awful licking and during the time the heavy metal box containing the four thermos jugs got loose and ran amuck in the cabin. At the risk of life and limb the stewardess managed to corral the thing and being unable to hold it down, opened the door of the lavatory, shoved it in there and slammed the door. That darned box nearly wrecked the ship. It broke the mirror, sat down * * * and squashed it like a collapsible opera hat and finished off by knocking holes in the roof. I was told that the ship had to be sent to Cheyenne for overhaul as a result.” 2d Pilot~Chicago "Was caught in a very severe line squall in Texas and came out of the top tail first at about 14,000. I ran into the storm at about 6,000 feet. Had absolutely no control of the ship and was almost ready to bail out. How long do you suppose I would have been up in a parachute?” 2d Pilot—Oakland "One never knows the intensity of a storm until he is up in the middle of it and taking a beating.” 2d Pilot—Chicago w it'* NOTES NOTES UNIT 10 FLIGHT PLANNING WITH ICING CONDITIONS “1‘- "Did we have to come to Verkhoyansk to find icing conditions?” Ice may form on an aircraft when the air temperature is below 35° or 36° F. (below 2° C.) and the aircraft is flying through visible water (preci pitation or cloud). The temperature range with greatest danger is 32° to 0° F. (0° to 20° C.) in cumulo—nimbus and towering cumulus clouds, 32° to 14° F. (0° to —10° C.) in strati-form clouds and in precipitation. Ice may form so slowly that it can be easily removed by operation of de-icing devices. It may form so rapidly that all de-icing attempts fail and the plane inevitably crashes. When an aircraft flies through air with icing temperatures and visible water, rate of ice accretion chiefly depends upon: (1) Airspeed of plane—rapid speed, rapid icing. (2) Size of cloud or rain droplets—large drops, rapid icing. (3) Density of the visible water—dense cloud or heavy rain, rapid icing. When icing temperatures exist, is icing generally more rapid in cumulus cloud or stratus cloud? In thin stratus or dense stratus? __________ In rain or in drizzle? ______________ Three types of ice may form on aircraft:1 (1) Frost—like the frost on ground objects. This forms when an ' aircraft passes from cold air into moist, warm air. It is not very serious, but may ice up the windshileld. Also frost may accumulate on a plane sitting out overnight. This frost sometimes increases drag to the point where the plane cannot take off. Sweep frost off the wings before attempting take—ofi'. (2) Rime—granular and milky in appearance. Forms on leading edges when an aircraft, in icing temperatures, flies through clouds with small droplets. Rime deforms air foils, chokes instruments, adds weight; but it breaks off easily. (3) Glaze—a coating of clear ice. Forms when flying through rain or through dense clouds with large drops, and with air I This is in addition to carburetor ice—which is a separate and serious problem. Carburetor ice can form with temperatures anywhere from below freezing to 70° F. or higher. The carburetor temperature indicator gives warning: When the carburetor temperature approaches the freezing point, turn on carburetor heat. FLYING THE WEATHER temperatures near or not far below freezing. Forms on leading edges and spreads backward along wings and other surfaces, adhering firmly. Danger is due to weight, deforming of airfoils, and vibration. When flying, you often will not have information about the tempera- tures at various altitudes. It will be necessary, on such occasions, to estimate the temperature. With no turbulence and no temperature inversion, the upper air temperatures can be approximated by noting the surface temperature and subtracting 3° F. for each 1,000 feet of height above the surface. When figuring icing zones, however, you should allow yourself a safe margin, and should remember that either turbulence or temperature inversion can easily upset your calculations. When ice flecks begin to form on the windshield, get out of that cloud or precipitation and do it now! PILOTS’ COMMENTS "Icing seems to increase when flying over mountain peaks where the turbulence increases.” Pilot—Salt Lake Div. "I brought a west-bound trip down through an overcast at Salt Lake which a pilot had climbed up through only a little over an hour before on an east-bound trip. The east-bound trip reported very slight amount 'of ice, but I collected a good 1% to 2 inches of time ice.” Pilot—Salt Lake Div. "December 1936: Cg—Dm trips flying west. Both same altitude, 15 minutes apart, 1st section arrived for fuel, no ice encountered. Section 2, flying same altitude IS minutes later reported icing conditions.” —Des Moines "I have flown several trips at less than 90 miles an hour air speed which prevented icing. Over 90 m. p. h. the icing was so severe that the ship would lose altitude.” Pilot—Cleveland Div. "The amount of ice collected depends upon the number and structure of moisture particles that strike the exposed surfaces—hence, it is rea- sonable to assume that while flying through an icing condition, the amount of ice collected will be proportional to speed and resulting changes in airflow about the surfaces.” Pilot—Salt Lake Div. "The largest load of ice I ever got was with temperature at 20° below zero.” Pilot—Cleveland Div. "Last winter I took on quite a load of ice at temperature of 8° F. at surface to 12° F. at 7,000 feet. De-icer would crack up the ice, but it froze to the rubber so tight it would not blow off. Air speed dropped to about 130 m. p. h. and the ship landed plenty hot.” Pilot—Omaha Div. "The pilot usually winds up with the knowledge that under any condi- tion which offers the possibility of ice formation, it is essential to have some sure way out of the ice-forming area at all times. Any ice-forming condition can prove to be too much for a ship to carry, or can set up destruc- tive vibration. Always have a way out. Even with our modern de-icers, slinger rings, etc., one finds that the more experience one has with ice, themore one is inclined to enter icing conditions with caution and with a positive alternative course of action mapped out in the mind.” ‘ Pilot—Cleveland Div. "I think that most of us by this time realize the importance of keeping out of icing conditions and will not fly into known hazardous icing even though our planes are equipped with tie-icing equipment.” —Iowa City t‘rsfirifi' The cross-section drawings on this page and the next show aircraft courses (represented by arrows) many of which run through clouds and precipitation. Lines showing temperatures critical to icing reveal that some of these courses through clouds and precipitation are free from icing danger while others hold serious icing danger. Studying each drawing separately, color red all very dangerous courses, color blue those courses (on some drawings) with slight risk of icing, and color green the preferable courses. (Ice frequently forms on aircraft when air temperature is slightly warmer than the freezing level; while performing this exercise, however, consider that the routes having temperatures above freezing are safely on the warm side of about 36° F. or 2° C.) CUMULIFORM CLOUDS . __‘__/-... /%H / MW; // %/////M§% 'y. 32.F A ' ”/2 / // /: ‘W---‘.u‘. MM ,3» l Moi/E FREEZ/N6 m... a 0°F 32°F ABOVE FREEZING Imwwmwlmmw b —_/ FREEZING 'ho .i , I] I’/ Ill/IllIII’IL/llulll/l/l/AU” 0°C /////“/” I/l ”/"l/I’W 460% Mm ’/I ”ll/’1 7/1 ///////,”H / II ////II [Ill/Illl/I/fl/l/U 20F / ll/ll/l/ I/I// ’17 0°C 3 _ plumml II, I ’7 INVERSION II /,/I///’ 0),] /I,/ 11.”!!‘1 ll d UNIT lO—FLIGHT PLANNING WITH ICING CONDITIONS STRATIFORM CLOUDS ABOVE FREEZ/NG l STRATIFORM CLOUDS WITH PRECIPITATION V / 52°F ///////: %/// . 1,1/ / 0°C u. I, (III/I’mlljél JIIII/I/Ill/l’lllll ,/ I, —‘:d ABOVE FREEZING O // / ///],Il// l I’ll/Ill, o c ’ // ABOVE fREEZ/NG ” I ' I,” II/ 32.F 'mnnvmul'” ' O C INVERSION zlllj’ I I / I l I I (I) ll __u//./1:J_L1u Sham/1m f _ .65. W, - W ’ //; 3, 0°C A FREEZING ABOVE FREEZING —4-— \>\\\\\ ; -\ \ \\ “ L régg‘ffia kg \ 32°F \\:\ \\f\\~- Ky §\\\_ 0°C INVERSION yum-— 14°F a ,1 - ,7/11” , W//.///j’// 0M t/fll/i/ //m My, , MW /////// ”I, // Mm / . // 7: 44 o 15/ 43/ /, , -../ m ‘ {r/ /’-' / ”7"” O C V ,.oy£ l/fl/M/A A's/M Fkgt'zms ”' It]??? h 66 FLYING THE WEATHER 10M \ wa 095 a? -20\ .a 3 A \\\\\\\\ -\ 1020 n w \\§\\\\\\\\\\\\ E a c _scALE_ i I j ' : I 300 MlLES er 4; 1940 - 7330 £57 FLIGHT PLANNING PROBLEMS At 1440 EST, December 4, 1940, you Were preparing to make a nonstop flight from La Guardia Field (New York) to Chicago, Ill. The direct airway from New York to Chicago runs as follows: New York—Kylertown—Cleveland—South Bend—Chicago. On Map No. 26, mark this airway with straight lines connecting the cities named above. At 1440, while preparing for your flight, you studied the map of 1330 EST (Map No. 26). According to the map, could you have MAP NO. 26 cleared at 1330 for contact flight from New York to Chicago? ________ Could you have cleared at 1330 EST for instrument flight from New York to Chicago? _____________________ Explain your answer: _________________________________________ Next you read the 1435E teletype sequences.2 According to these recent reports, are you now able to clear for the flight? __________ Contact or instrument? __________________________ Explain your answer: ______________________________________________________ ’ Stations on your airway include: New York. Newark, Cleveland, and Chicago. 1435E MA MADISON WIS. SPL 762F— 081/28/25111/971 RD ROCKFORD ILL. E862F- 075/32/32—>/‘7/971/INTMT L— MK MILWAUKEE C SPL106GD5F— 071/28/27l\.10/969 CG CHICAGO C E106663EZL—K— 071/33/30/‘11/970 UK MUSKEGON MICH. 1767S— 064/29/25——»\.5/968 GR GRAND RAPIDS MICH. C1066S— 061/29/27—>\9/966 LJ LANSING MICH. N 1061VZL—F— 075/25/25T/‘13/969 DT DETROIT MICH. C SPL E1863SW— 085/26/20—>\.17/974 CV CLEVELAND OHIO N E20611/2S— 112/26/24/‘15/980 ER ERIE PA. El562VS—BS— 108/23/211‘21/980 DK DUNKIRK N. Y. El263/4VS—BS— 23/201/‘25+/977 BJ BUFFALO N. Y. N E1061VS— 102/23/20T/‘25+/977 EA ELMIRA N. Y. E7067 142/21/18T20—l988 WI WILKES BARRE PA. E806 203/23/15122+/008 NK NEWARK N. J. C(ID/ 224/30/7T/‘l3/018 LG NEW YORK N. Y. COD/3569 230/30/13\18/020 You read the following airway forecasts (regional and terminal forecasts): CGLV MKBJ CGNK IDPG NABJ CGDT Milwaukee- Chicago— Indianapolis- Nashville- Chicago— Chicago- Bufl'alo Newark Philadelphia. Buffalo Detroit Louisville MRBO IDCC DYGR DTWA DTWK DYDT Martinsburg- Indianapolis- Dayton- Detroit— Detroit- Dayton- Baltimore Cincinnati Grand Washington Woodward, Detroit Rapids Pa. CGGR BOEA PTER COER Chicago- Baltimore- Pittsburgh- Columbus- Grand Elmira, ' Erie, Pa. Frie, Pa. Rapids N. Y. A RDG OF HI PRES XTDS FROM NWENG SWWD TO THE GLFMEX AT 0730E DEEP LOW CNTRD XTRM WRN WIS AT 0730E WILL CONT TO‘MOV RPDLY ESEWD TO ERN PTN (portion) OF LWR MICH BY 1930E WITH CONTD STEEP GRADIENT OVR THE RGN. OVC WITH LGT TO OCNLY MDT SNW OVR THE GRTLKS RGN WILL SPRD SEWD INTO THE PA MTNS EARLY IN PRD. CIG GNRLY 1 TO 2 THSD AND VSBY 1 TO 3 BUT VSBY OCNLY )6 IN SNW AND CIG LWRG TO 5 HND TO 1 THSD OVR MICH AND AFT 1400E IN VCNTY OF LAKE ERIE AND OVR THE MTS. ICG IN CLDS. OCNL LGT SLT OR FRZG RAIN LKLY OVR MICH AND XTRM NRN IND. IN CNTRL AND SRN PTNS OF OHIO AND IND AND NRN KY OVC AT 15 TO 35 HND AND VSBY 5 TO 15. SCTD TO BRKN CLDS AT 4 THSD TO UN L LOUISVILLE NASHVILLE AWY WITH VSBY 5 TO 15. OVC AT 3 TO 6 THSD OVR THE MTNS PRECDG THE SNW AREA WITH VSBY 5 TO 15. E OF THE MTNS INCRG HI CLDS BCMG BRKN TO OVC. VSBY 5 TO 15. WNDS ALF 40 TO 60 MPH 210 TO 250 DEGREES UP TO 5 THSD AND 260 TO 280 DEGREES ABV 5 THSD SHFTG TO 280 TO 320 DEGREES AT LWR LVLS OVR SRN LAKE MICH LATE IN PRD FLWG COLD FRONT END UNIT IO—FLIGHT PLANNING WITH ICING CONDITIONS GR (Grand Rapids) TRML. OVC WITH LGT TO OCNLY MDT SNW AND SOME FRZG DRZL OR SLT LKLY. CIG GNRLY 4 TO 8 HND AND VSBY 1 TO 3 AND OCNLY 1/2 IN MDT SN W END SN (South Bend) TRML. OVC WITH INTMT LGT SNW OR FRZG DRZL. CIG GNRLY 4 TO 8 HND. VSBY 3 TO 6 BUT NEAR 1 AT TIMES IN PCPN END FW (Ft. Wayne) TRML. OVC WITH INTMT LGT SNW OR FRZG DRZL. CIG 1 TO 2 THSD LWRG TO 4 TO 8 HND BY 1400E. VSBY 3 TO 6 BUT NEAR 1 AT TIMES IN PCPN END CO, (Columbus) DY (Dayton) ID (Indianapolis) CC (Cincinnati) LV (Louisville) TRMLS. OVC AT 15 TO 35 HND AND VSBY 6 TO 15 END BJ (Buffalo) CV (Cleveland) AX (Akron) TRMLS. OVC WITH INTMT LGT TO MDT SNW. CIG 8 TO 15 HND LWRG TO 4 TO 8 HND AFT 1600E. VSBY 1 TO 3 AND OCNLY 1/2 IN MDT SNW END PT (Pittsburgh) TRML. OVC AT 3 TO 6 THSD. INTMT LGT SNW BGNG BY 1300E WITH CIG LWRG TO 15 TO 25 HND. VSBY 6 TO 15 LWRG TO 1 TO 3 IN SNW END HX (Harrisburg) TRML. HI BRKN CLDS TO OVC LWRG TO 3 TO 6 THSD AFT 1800E. VSBY 6 TO 15 END END You decide to fly on top of the overcast, Where possible to do so Without going over 8,000 feet. In event you run into impassable weather, where do the weather map and the forecasts indicate that you will find better weather? In what direction from Chicago will you pick your alternate terminal for this flight? You take off at 1500 EST. While in flight you pick up, by radio, weather information con- tained in the following teletype sequence reports. (In 1940 you, of course, received this radioed information in plain English; during wartime you would receive it in code form and de- code it with aid of the daily code sheet. Here we present it in tele- type form, as you would see it if at a station.) 1535E MA MADISON WIS. 763F— 088/26/23113/973 RD ROCKFORD ILL. E863F— 081/32/29—->\13/973 MK MILWAUKEE WIS. C SPL E10668 081/27/24l\9/972 +6NE CG CHICAGO ILL. N SPL 1066(DZK— 075/33/31—»/‘11/971 UK MUSKEGON MICH. E17668— 071/28/24l\.5/970 GR GRAND RAPIDS MICH. C 1266S—H O68/29/26—>\7/968/OCNL SP- LJ LANSING MICH. N SPL 56 lVZL—F— 078/26/26—v/‘12/970/INTMT E— DT DETROIT MICH. C E1864SW— 064/26/239/‘12/970 CV CLEVELAND OHIO. C E3065H 112/28/22/‘16/980/OCNL S— ER ERIE PA. E1063S- 108/24/21T/‘19/981/BS— OCNLY DK DUNKIRK N. Y. E156611/4VS—BS— 26/20/16 BJ BUFFALO N. Y. X SPL E106 l/2VS 102/23/21T/‘24+/977 EA ELMIRA N. Y6. E6067 139/22/19T22—/987 DUBUQUE MA RD CG UK DT CV ER DK BJ WI NK LG MA RD MK CG UK GR LJ DT CV ER DK BJ EA WI NK LG 20,000’ — 15,000’ — Io,ooo’ — s,ooo’ —- CHICAGO SOUTH BEND CLEVELAND 1635E 96SW—F—— 098/26/221 14/976 E663F— 091/31/291\.13/975 N 106662K— 081/32/31—>\.11/973 SPL E 17 6 081/27/2315/973 N 561VZL—F—— 085/27/27/‘5/972 C E1863SW— 088/27/24~+/‘12/975 C E3065H 105/29/22/‘15/979/ INTMT S— SPL E15696S2—BS—H— 108/25/22T/20+/98l El56®lS—BS— 25/22/23—/803 C SPL 2063S—BS- 098/24/21T/23—l977 E6067 139/22/13T25/987 SPL E606SSW— 176/25/17T/‘20—l001 COD/3568 203/31/19 T 20/012 C —(lD/3568v217/13/19 T20/016 1735E 663/4SWF— 108/23/20 1.16/979/ SNW CIG E663SW—F— 098/28/251 \13/977 C E1263SW—F~ 098/28/22l9/977 [OCNL SP— MXD N SPL 106661L—F—K— 088/33/31—’\9/975 PIREPS TOVC 50MSL ICE10 TO 50MSL E206 091/26/2218/976 C 1665S—K— 085/27/2317/973 N E561VZL—F— 088J27/27—>/‘7/973 N56lZL—F— 091/27/26/‘11/976 C E3565S—H 108/30/22T/‘13/980 286(1D11/2VS—BS— 112/26/23T/‘18+/982 SPL 206QD3S—BS— 26/22/23— N 226 11/2VS—BS— 098/25/23 T/‘21—l977 E106IS— 146/20/17T 17/989 SNW CIG 306SSW— l76/25/19/‘20—l001 C 6/ 196/31/21 T12/010 C E40—GD/(ID7 207/32/22T /'28+/013 WI NK LG WILKES BARRE PA. E806 193/24/141/‘19—005 NEWARK N. J. C 6/356 217/29/13T/‘14/016 NEW YORK N, Y. C 6/3568 224/30/15T15/018 At 1845 you were flying at 4,000 feet between cloud layers about midway between Cleveland and Chicago, and picked up weather information contained in the following 1835 E weather report: ’ 68 FLYING THE WEATHER ‘5 t I \ § ' ‘ L i V g _ £2» é , , a , // , w \‘79 ‘ i‘ ‘ '6 63%? “l ' ”310/ “33352 7020 \ ~13- / I / 3* 28// 1 ~' 2 _/ 83 ’ // V , ' / ‘7. 83 * +30/ / , 2. O , 12 T // )2 36¢- x _ 2/ gig/+20 / k a x ,w», V/ /, /‘3 /’43/fl76 // W? {A was we ’ g 2 49/133,: / /, 4//// \ '38 i 6159 , RES 7 4‘?” an ’beKy/ny’ P S “U {62/ 26’4128/ “Sioux CITY 34/ 8‘??er o4 ’34“ 180 , ‘T \o’ 233% +6/‘—7 / 12’ 2/1 p ” ’ :64 FA / at ’ 2216:.“ BY” " / at- 30 06, 36253??? , / 1020 01ch ,,/ gwflfi / V 9}” T A 2 '92? r 3" 108 o .a.,,,,H, “26*, ; 7, ”WW /. I“, +20 2 1%” s c E i + a i ‘ 7 11:. \c, 26 2% n 1 AL n n 93 , 0M“ x, 300 MILES ’ +25” 36727. +1 1 % 09¢?me 4! I940 - 1930 £257 a 2 E K W MAP NO. 27 183513 CV C 21$5S—F— 112/30/23/‘11/981 Following the 1835E report, the tower at Chicago broadcasts to MA 27$2$_ 125/22/201 11/984/SNW CIG ER SPL 226378— 119/27/23T /'17+/983/ OCNL BS— you: “Pilots report heavy ice 2 to'5 thousand. Change altitude from RD E66311/28*F— 119/26/261\8/983 DK SPL 20630958— 26/23 /‘16/ CIG RGD 4 to 6 thousand. A plane attempting landing through icing belt at MK N SPL sealsw-K— 155/22/20 112/982/ SNW cm. BJ N 12$ 11 /4VS—BS— 102/26/23T'\19—/978/ SNW CIG 1832 iced up and hit ground.” CG N SPL 12$6®IS—F—K— 098/32/31 1\.9/979 EA 35$5S— 146/ 21/ ml 20/989 What do you think your procedure should be now? ______________ UK 186358- 102/25/2217/979 WI SPL 286938— 180/24/21/‘17/002 LJ N6695CD12L-F— 091/26/2615/976 NK C SPL 4069 183/32/22T'\12/006 """"""""""""""""""""""""""""""""""""""""""" DT X SPL 4VGBGD2F— 098/28/28/‘10/978 LG (13/ 173/34/24\,6/996 _____________________________________________________________ UNIT 10—FLIGHT PLANNING WITH ICING CONDITIONS 69 eqooo’ 20,000’ —— \ a Q SCALE .5000: § \ . . ALTO—CUMULUS .5000!— ' 100 mi/es ‘é-B ‘ y ,./""—"' “~--~--_- 'IO°C _____-___-. __"_“~"\-- «are ALTogTRATUS Horizonfa/ @:4:~>._’?r 6;? . é @ 0“" -- >3 _ Q @_ 3?; IOIOOOI— Io,ooo’ — '\_IO'C _-_~‘_ -- C .75.? -- “—--— _.--___--___-..______.___.._____._-__ -|o°c _-_.._ CUMULUS and STRATO gym-US STRATO-CUMULUS and NIMBO-STRATUS '. \\\_\ '/\‘ U /‘§ \/ . 5,000’— {1: Mt r“ " \_"\’“'\«$;r tad ‘x‘ ‘ :15} ‘5.°00'— 4% fi_, —‘ - :1; '1‘) 1 r ’- , _ ,£(£%i§g ~ . \\\ . *1» “Hr awe’ 1.; :3; _ - a: *mw*m fié I \\\\w\\\\\\\*,r . s. p ,, z * i * SOFT sNoWi’nv: FR: bf(Z¢(O\ \ \X)\ \ I I \ 4: r u 0°C I I I \ w ' g -— --— 34 we ask I59 30g I49 alt Ila I02 “5 2| I49 25 I90 36 |86 +6/ 7 '5 +33/ 6“ +38 2 ** +22/ 3L0 V+I6/ 3012"?” + 8/ 3H -2\ 5M6! 7 -32 L 30 22 3— 24 "V— .T 29 V .T 30 I4 23 I8 v; l9 104- 24 V” 20 "- 6- '0 30 30 SIOUX CITY IOWA FALLS DUBUQUE CHICAGO SOUTH BEND CLEVELAND KYLERTOWN WILKES—BARRE NEW YORK FIGURE 10C.—Cross-section (Iowa to New York) showing occluded front, December 4-, 1940. Explain why you choose this procedure: _______________________ What will probably happen to the occlusion during the next 24 73? 7"! if After landing, you are interested in the weather formation in which you found yourself, so you examine the weather map drawn at that time (Map No. 27). The pictorial vertical cross section (fig. 10D) is given to help you visualize the situation at 1930 EST. Maps N o. 26 and 27 show the movement of weather and the occlu- sion process. To help you more fully visualize the movement of the weather complete figure 10B, drawing a vertical cross section of the weather at 1330E between Dubuque and Cleveland: Place station models under the cross section, and use a drawing method similar to that used in drawing figure lOC. Draw the fronts, ceilings, precipitation and lower cloud forms as indicated on the weather map (Map No. 26). Draw from judgment (and after study of fig. 100) the distribution and types of clouds aloft. Estimate and indicate the zone with serious icing temperatures. Label your drawing. Consult the barograph chart (fig. 10D) and tell at what time the cold front passed Chicago: _____________________________________ What was the barograph reading (in millibars) at that time? _______ About how far (in miles) did the center of the low move from 1330 to 1930? ________________________________________ Why did the occluded front grow longer during the period from 1330 to 1930? ..................................................... 524786 0 — 43 - 6 hours? _____________________________________ .- _- _ _ -_ _ _ _ _ __ _____ Refer back now to Map No. 10, the weather map for 0230 EWT, December 18, 1942 (p. 25), on which you located the warm front. On that morning of December 18 you were at Boston and very anxious to get to Washington, D. C. Consult the map and the accompanying cross section. What was the weather from Boston to Washington? The air above the occlusion is warmer than the air at lower eleva- What caused it in this instance? ______________________________________ tion. This is called a temperature ___________________ General: Norm—This weather condition was constructed from reports of six pilots flying in the vicinity of Chicago during the period 1800 to 1900 EST. One pilot, with more than 5,000 hours in his log, picked up Ceiling: too much ice. Circumstances sometimes require that you fly in unfavorable weather conditions, but you must know your limitations and those of your plane. Only by experience will you discover those limitations. Even then the wise pilot gives himself a large margin of _ _ _ . safety. thbtlzty: MONDAY TUESDAY WEDNESDAY THURSDAY FRIDA 3E3 ' Eé‘é Egg Surface wind: BAROGRAPH BLANK BUREAU OF AERONAVYICS-NAYV DE" MILLIBARS The duty officer agreed to clear you from Boston to Washington provided you could show him a satisfactory flight plan including a satisfactory alternate terminal. What flight plan did you present for his approval? TO PUT UNDER THE OTHER END 70 FLYING THE WEATHER 130° 125° 120° 115° 110° 105° 100° 95° 90° 85° 30° 75° 70° 65° 45‘ 45" 40° 40' 35° 35° 2 M “185 > aggflififig \5562ga6\ 03‘“ 5 30° 30° ' UNITED STATES NAVY° 25° 49 November 22, 7.942- 02305 W 7 3331521, 45 12 ‘3%\ 25° 25 1023 SCALE v 1--—-——-t-—--—-L—-—-——-1 300 muss \ 120° 115° 110° 105° 100° , 95° ‘ 90° 85° 80° 75° MAP N0. 28 Zo,ooo’— ALTo;CUMUEus \ wit/S ALTO'- STRATUS 15,ooo’— ‘--‘ ——."'l°°C / 10,000,— 5000’— 298 I7 342 23 K 342. 32 f - .9 '6 I.5* ‘2 9 I2 9__,/0 20 v: as 3"“ 05 -T I4- .I5 DENVER GOODLAND CONCORDIA UNIT lO—FLIGHT PLANNING WITH ICING CONDITIONS 71 —— 20,000 .————-—-———— \ - h_.——_—_‘O°C .._.——-—— Verf/‘c'a/ _—‘-_ -I0°C ~--_ — :5,ooo’ l \ \ \ \‘ ~y ”PIJQM 36/:244- 44 212 46 2:3 .9: --2'\ 5.. , -3 43 —o« 34-w- , 42 v- - 45 -u- - as .on as as .03 KANSAS CITY ST. LOUIS LOUISVILLE "' " — ‘ 0°C #1:? lac , fix The? ALTo— sTpATus — 5,ooo’ ‘ ‘ m ‘w‘ mm mm Hum“ m w \ ‘ “‘\3"\'4’?At P“ \i\ I)‘\\ ‘ \\\v‘:\\, -'.. 46 an 46x. 203 45 f227 40 +8/‘ .59! +0 4” MO 431*!" - 45 V ° .35 'V' ' .08 02 .04- 40 .04 HUNTINGTON ELKINS WASHINGTON FIGURE IOE.—Cross-section (Colorado to D. C.) showing weather associated with frontal surfaces, November 22, 1942. FLIGHT PLAN: Classification of flight: (lourse : Altitude: Alternate Terminal: When approaching Washington you received radioed information concerning your terminal weather. The following sequence report gives the same information in another form: SPL 106194ZL088/36/31\15/983 PIREPS TOVC 50 MSL Write this in plain language: ________________________________ 442$ On the morning of November 22, 1942, you were at Knoxville, Tenn., and were ordered at 0200 CWT (0300 EWT) to fly to Wichita, Kans, immediately. Studying Map No. 28 and the accompanying cross section, outline. your flight plan: FLIGHT PLAN: Classification offlight: Co arse : Altitude: Alternate terminal (and why chosen): When you received your orders the aerologist at Knoxville antici- pated that the western Kansas weather would clear up by the time you arrived at Wichita. It didn’t. Upon arrival over Wichita you learned, by air temperature reading and observation of the top of the overcast, and by radio report from Wichita, that conditions remained much the same as at time of take-off. The only change was a reduced visibility—reduced to 1 mile—owing to fog and snow. Would flight regulations permit landing under those weather conditions? ________ What hazard or hazards would you encounter in landing? 72 FLYING THE WEATHER 130‘ 125' 120° 115° 110° 105‘ 100° 95° 90° 05° 80° 75° 70° 65" W 450 \ : 45‘ Xvi I ,. " ‘g/l/éfiz -— .- 9 ‘ , ,- I, b 206/ 1 , 69 ’5‘ ‘QON { - Il/ Kfi'fl‘i/ ‘029 40‘ . 16 , ALBA / x x 40‘ / ( I \ 4 g (1%“ // LACK ’* 23’ 573 ' ’ /:fl 2 - ‘* .2; /5:«~ 2° 01 ’ 4». v .3 “(’0‘ ,p'- ’I ,«E . ,. / / , - fly "4 i Q—Sqlézfi‘fiig ‘ 1 7 « 9 .352'0- v (1 2‘} ’ ‘ a . “ « ' m/ , 3 w . , , 5/ I 3 a, b 21. \ 35° ‘ 35' .17“ 17 v 30. 9 '33 _ ,30' 5f 245 '15:: 4 ' V - * 19 ' ‘ ‘~— “44'— b _ _— —- —- 'a’\’ bag \NOK‘¢ 12V . I . “R3890“ x ‘9 4i CPR: 13:» ; 34v < _. '4 «Lyesypgg’f; é . ,. j, ‘, V ,0 «21% ”Elk ,49‘ :4 . UNITED STATES NAVY- 3397'! 27,252 We: a“ @305 ngfiyf 2" 0 January 18,1943 - 0230 ewr 8496 1:; What—4 ‘ "i ‘ > _.. / 120° 115° 110° / 105° 100- y ' 95° 90° 85° 80° w’ MAP N0. 29 fir‘firi’? On the morning of November 22, 1942, your friend, Don Launer, was at Chicago and at 0200 CWT (0300 EWT) wished to fly to New Orleans. He had an instrument rating. Was it possible, in accordance with Navy flight regulations, to clear for New Orleans via St. Louis and Memphis? ____________ Was it possible to clear for New Orleans via Louisville, Nashville and Birmingham? ________________ Was it possible to clear via Cincinnati, Knoxville, and Birmingham? ___________________ Study Map No. 28 and the cross section (fig. ICE) and tell which of these three routes he should have chosen to fly: In what direction from New Orleans (east, northeast, north, north- west, or west) should he have selected his alternate terminal? ________ _ Explain why: ________________________________________________ Skits? At 0100 MWT (0300 EWT) November 22, 1942, would it have been possible for a naval aviator with instrument rating to clear from Denver for flight to Washington via Kansas City, St. Louis, Louisville, Hunt- ington, and Elkins? _________________ Explain your answer? Which of the following three routes would you recommend for flight from Denver to Washington starting at 0100 MWT? Check your choice: 1. Denver-St. Louis-Nashville-Roanoke-Washington ___________ 2. Denver-St. Louis—Indianapolis-Pittsburgh—Washington ______ 3. Denver-Omaha-Chicago-Pittsburgh—Washington ____________ Your friend, “Rusty” Wilson, was at St. Louis and ordered to fly to Dodge City at 0130 CWT, November 22, 1942. He had instrument rating. Was it possible to clear from St. Louis to Dodge City via Kansas City- and Wichita? __________________ Via Springfieldand Wichita? ________________ Which of these two routes would you recommend? _________________________________________________ According to the cross section (fig. 10E), at what elevation (mean sea level) should he fly to have fullest freedom from icing danger? ________ first?! On January 18, 1943, you were the duty officer at Boston, Mass. At 0300E Commander Wilco came into the office and wanted clearance on a flight to San Francisco. His mission was urgent and he desired ' information on all possible routes to the west coast. UNIT IOmFLIGHT PLANNING WITH ICING CONDITION You produced the 0230 EWT weather map (Map No. 29) and pointed out to him the weather conditions for the various airways. What was the flying weather for the routes as listed below: 1. Boston-Albany-Bufl'alo-Detroit-Vlinneapolis—Miles City-Seattle: 2. Boston-New York-Cleveland-Chicago-Omaha-Cheyenne—Salt Lake City—San Francisco: 3. New York-Philadelphia-Pittsburgh-Columbus-Kansas City- Albuquerque-Los Angeles: 4. Philadelphia-Washington-Bristol-VIemphis-Ft. Worth-El Paso— Tucson-L03 Angeles: U. 8. GOVERNMENT PRINTING OFFICE :1943 0 - 524'!“ 73 5. Washington-Adanta-Vicksburg-Ft. Worth: Routes Nos. 1 to 5, above, include all of the established east-west air routes across the United States. Was there any other possible course, all these airways, that, according to the weather map, Commander Wilco could fly? _______________________ If so, what was the weather along that route? ______________________________ Did you give him clearance for San Francisco? ____________________ If so, by what route? __________________________________________