國外航校私照飛行員地面課Lesson11

1、Lesson 11Weather Theory Todays TopicsBegin Weather TheoryPass out and review examsAtmosphereMixture of gases78% nitrogen21% oxygen1% other Various Atmospheric LevelsThermosphereMesosphereStratosphereTropopauseTroposphereWhy Does Weather OccurEvery physical process of weather is accompanied by, or is

2、 a result of, heat exchangesUnequal heatingUnequal heating of the Earths surface causes differences in pressure and altimeter settings.If the world didnt turnCoriolis ForceDeflects winds to the right in the Northern Hemisphere. Caused by they Earths rotationThe deflections caused by this force are l

3、ess at the surface due to the slower wind speed.The wind speed is slower at the surface due to the friction between wind and the Earths surface.The World TurningPressureHigh pressure seeks low pressure.The greater the change in pressure, the stronger the windsHigh PressureCirculates outward, downwar

4、d, and ClockwiseRidgeAn elongated area of high pressure Low PressureCirculates inward, upward, and counter-clockwiseTroughAn elongated area of low pressure Air MassesAn extensive body of air having uniform moisture and temperature propertiesAir masses form in Source Regions, for example:Maritime Pol

5、arArcticContinental PolarMaritime TropicalFrontsBoundary where 2 or more air masses meetCold Front Cold airmass is moving a warm airmassLike a “snowplow”Possible Weather Associated with this Front Cumulonimbus cloudsShowery precipitationSevere Weather Thunderstorms Warm Front Warm airmass overtaking

6、 a cold airmassLike a “Blanket”Weather Associated with this frontCirriform and Stratiform cloudsFogLGT to MOD steady precipitation Poor VisibilityStationary Front When forces of two air masses are equalThe weather is a mixture of a cold front and warm frontInfluences the weather in an area for daysO

7、ccluded Front Occurs when a fast moving cold front approaches a slow moving warm frontFronts: Critical ThinkingWhat can you expect as a pilot as you cross frontal boundaries?How does a pilot know when they cross a frontal boundary?Stable Air Stratiform Clouds and Fog Smooth Air Continuous (Steady) PrecipitationFair to Poor VisibilityUnstable airCumuliform Clouds Turbulent AirShowery PrecipitationGood VisibilityCloudsDivided into Four FamiliesHigh CloudsMiddle CloudsLow CloudsClouds with extensive Vertical DevelopmentNimbus (Rain)In the METAR