Air Environment1 Air Environment Module 3 Aviation Weather Ted Spitzmiller

Air Environment2 WEATHER SYSTEMS 1.Air Circulation 2.Weather Elements 3.Moisture & Clouds 4.Weather Systems & Changes Significance of italics—immediate recall Location in your book (x)

Air Environment3 Source of Weather Sun heats the earth by radiation (1) Sun Earth 15% absorbed by atmosphere 35 % scattered or reflected 50% absorbed by the Earth

Air Environment4 Earth’s Seasons Varies Circulation (3) Earth’s Axis tilted 23.5 degrees Seasons dependent on –(Spring/Summer/Fall/Winter) Days and nights of equal length on spring and fall equinox Mean distance from Earth to Sun. 149,597,870,691 km or ×10^6 mi (93 million miles) Equator rays Sun Equator rays

Air Environment5 Weather Elements (9) Wind Temperature Pressure Moisture

Air Environment6 Atmospheric Pressure (13) Weight of air sea level –14.7 lbs\sq –29.92 inches mercury (hg) –761 mm – mb Barometer is used to measure air pressure (13) Varies with altitude of reporting station — corrected to SL Aneroid barograph provides a permanent recording of pressure (13)

Air Environment7 Types of Pressure Systems Low < 29.92” generally poor WX air cools as it rises (as a bowl fills up) High > 29.92” generally good WX descending and warming

Air Environment8 Wind Pressure gradients Local wind systems –Land and sea breezes –Mountain breezes The Beaufort Scale can be used on land or sea and is used for estimating wind velocity (10)

Beaufort Scale Air Environment9

= High Pressure Pattern

Air Environment11 Low Pressure Pattern =

Air Environment12 Atmospheric Circulation Around Pressure Systems Earths rotation –Equatorial 1000 mph, poles 0 mph Coriolis and surface friction effect deflects air to right (record) –An object in northern hemisphere is deflected to the right by coriolis force Cyclonic vs anti—cyclonic (counter—clockwise and clockwise)

Air Environment13 Pressure Variations Trough — elongated low extending from central low Ridge — elongated high usually extending from central high

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Air Environment15 Temperature (12) Heat is the total energy of all molecules within a substance (12) –Water boils at 212° F (100 C °) and freezes at 32° F (0 ° C) (12) –Absolute zero 459 degrees F, or -273 C, or 0 Kelvin Standard 59 sea level ( ” hg  F = (1.8 x C) +32  C = (F/1.8 ) – 32  F = 9/5 C +32 What is the equiv of 15° C STD lapse rate –3½ degrees F per 1000 feet (unsaturated air) (2 ° C) Temp and wind produce a wind chill factor (10) 9 * 15 = 135 = = 59° 5 1 5

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Air Environment17 Moisture and Clouds 3 (19) Condensation Dew point Fog Precipitation Saturation Relative humidity

Air Environment18 Moisture – Humidity (19) Relative humidity — % capable of holding (example...) –Air holding all the moisture it can is said to be saturated (19) Dew point — given pressure air must be cooled to become saturated (19) Example… bathroom shower Saturation affects stability of air

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Air Environment20 Clouds (20) Visible moisture condensed on dust –Hygroscopic nucleii Classifications –Stratiform — cool, dry, stable, smooth, poor visibility, drizzle –Cumuliform — moist, warm, unstable, turbulent, good visibility, rain –Cirrus—very high thin wispy clouds

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Air Environment22 Weather Systems and Changes 4 (27) air mass front hurricane thunderstorm tornado

Air Environment23 Air Mass Characteristics - Temp Pressure Moisture (27)

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Air Environment26 Atmospheric Stability Air tends to flow horizontally May be displaced — lifted –Terrain –Thermals –Air mass differences Lapse rate and saturation determines stability –unsaturated = normally stable –saturated and cool = normally stable –saturated and warm = normally unstable Stable air resists displacement Unstable air readily moves vertically

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Air Environment28 Frontal characteristics Cold — fast/slow, cumulus, good visibility Warm — slow, status, poor visibility Stationary Occluded Frontal passage — wind shift

Air Environment29 Cold Front (28) Cumulus clouds, local heavy rain, good visibility

Air Environment30 Warm Front Stratified clouds, steady rain, low visibility

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Air Environment33 CumulusStratus MoistureHeavy Localized RainLight to moderate Wide Spread VisibilityGoodPoor TurbulenceYesNo

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Air Environment37 Cirro-Stratus

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Air Environment40 Thunderstorms (29) Air mass & frontal Requirements –Lifting –Moisture –Unstable air Stages (29) –Cumulus – building –Mature –Dissipation

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Air Environment45 Tornados (30) Precautions (31) GO to a basement Stay away from windows

Air Environment46 Mountain Waves Lenticular Lee side turbulence

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Air Environment49 Jetstream

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Air Environment51 Icing Rime clear

Air Environment52 Turbulence Light Moderate Severe

Air Environment53 F, MPH, mbars

Air Environment54 Charting you own weather