国外航校私照飞行员地面课Lesson.ppt

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1、Sierra Academy of Aeronautics,Weather Hazards/ServicesLesson 12,Weather HazardsWake Turbulence,Todays Topics,Thunderstorms,Thunderstorm,Three ingredients to a thunderstormLifting Action Unstable Air MoistureStages of a Thunderstorm CumulusMatureDissipating,Thunderstorms:Critical Thinking,How far awa

2、y should pilots stay away from thunderstorms?Why should pilots remain that far from a thunderstorm?What other significant weather can be associated with thunderstorms?,Fog,Fog,TypesRadiation FogAdvection FogUpslope Fog Precipitation Induced FogIngredients for Fog Temperature-Dew Point spread is less

3、 than 2 degrees Celsius and decreasing,Radiation Fog,Advection Fog,Up-Slope Fog,Precipitation Induced Fog,Icing,Icing,Types of IceClear Rime Mixed Frost Ingredients for IceVisible MoistureTemperature at or below freezing,Icing:Critical Thinking,Can a VFR pilot fly into known icing conditions?If icin

4、g accumulates on your airplane what should you do?What types of features on an airplane prevent icing or de-ice the airplane in flight?,Weather Facts,Standard Pressure29.92Standard Temperature15 degrees CelsiusStandard Lapse Rate 2 degrees Celsius Per 1,000 Feet,Land Changes Temperature faster than

5、Water,Sea Breeze/Land Breeze,As altitude increases temperature generally goes?UpDownStays the sameWhy?,Review?,Occurs when the temperature goes up with altitude.Acts as a lid for weather and pollutantsOver time can lead to low visibility due to fog,haze,smoke and low clouds.,Temperature Inversion,De

6、w Point is the temperature at which the air would be saturated(100%Relative Humidity)If Temperature and DP are within 2 you will have visible moisture(clouds or precipitation),Dew Point,Amount of moisture in the air compared to the total amount that can be held at that temperatureWarmer air can hold

7、 more moisture,Relative Humidity,Temperature and dewpoint converge at about 4.5 per 1,000 feetYou can estimate Cumulus cloud basesTemp 85 Dewpoint 6718/4.5=4,000Cloud bases should be 4,000 feet AGL,Estimating Cloud Height,Change of State,Dew forms when objects cool to below the dew point and water c

8、ondensesFrost forms when objects cool to the below the dew point and below freezing temperatureswater vapor turns to frost via deposition,Dew and Frost,Turbulence and Wind Shear,Turbulence caused by thermalsThermals-Rising air heated by warm surface below,Convective Turbulence,Stable air forced over

9、 a mountain ridgeExpect it when winds are+25 knots perpendicular to mountain ridges,Mountain Wave Turbulence,is the turbulent movement of air masses in the absence of any visual cues such as clouds,and is caused when bodies of air moving at widely different speeds meet.1,Clear Air Turbulence,Sudden

10、drastic shift in wind speed and/or direction Can occur at any altitude and in any direction,Wind Shear,A microburst is a very localized column of sinking air caused by a small and intense downdraft.,Microburst,Microburst,Other Hazards,Gasses,dust and ashHighly abrasiveWill pit the windshield and lan

11、ding lightsClog Pitot-static systemClog air filtersShut down jet enginesCan look similar to clouds,Volcanic Ash,Wake Turbulence,Wake turbulence is turbulence that forms behind an aircraft as it passes through the air.This turbulence includes various components,the most important of which are wingtip

12、 vortices and jetwash.Heavy,clean,and slow aircraft create the most wake Turbulence.,Wake Turbulence,Jetwash refers simply to the rapidly moving gases expelled from a jet engine;it is extremely turbulent,but of short duration,Jetwash,Wingtip vortices are much more stable than jetwash and can remain

13、in the air for up to three minutes after the passage of an aircraft.Wingtip vortices occur when a wing is generating lift.Air from below the wing is drawn around the wingtip into the region above the wing by the lower pressure above the wing,causing a vortex to trail from each wingtip.,Wing Tip Vort

14、ices,Wing Tip Vortices,Taking off behind a large aircraft,rotate prior to the rotation point of the large aircraft and maintain a higher climb rate,or side step the runway if able.,Wake Turbulence Avoidance,Arriving behind a large aircraft,fly a steeper approach and touch down beyond the touch down point of the large aircraft.,Wake Turbulence Avoidance,