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Three requirements for a thunderstorm:
- Unstable air
- Lifting action
What do roll and wall clouds indicate? Where do they form?
- Indicate the presence of low level wind shear and extreme turbulence
- Occur in severe and fast moving thunderstorms
A _____ forms on the surface at the leading edge of an advancing thunderstorm
Microburst are an intense, highly localized downward atmospheric flow with velocities of ____ to over ______ feet per minute.
What methods can be used to detect a microburst?
- Visual cues - large temp/dew point spread
- Wind shear alert systems
- Pilot weather reports
- Departure/Arrival weather reports
What are the recommended procedures to avoid a thunderstorm?
- Over the top: 1000' for every 10 knots
- Underneath: 1/3 distance from ground to cloud base
- Penetrate: lower 1/3 of storm; below freezing level
What is the procedure if you must penetrate a thunderstorm?
- Penetrate perpendicular
- Penetrate below the freezing level or above the -20°C level
- Minimum altitude 4000'-6000' AGL above the highest terrain
Thunderstorm common sense:
- Don't takeoff or land if a thunderstorm is approaching
- Don't fly into a cloud mass containing embedded thunderstorms without airborne radar
- Avoid flying under a thunderstorm, even if you can see through to the other side
Why do you want to fly over the top, at least 1000 feet per 10 knots of wind speed at cloud top level, to avoid a thunderstorm?
Because it allows an altitude margin for turbulence and hail
Why do you want to penetrate the lower 1/3 of a thunderstorm?
Because most storms are most severe in the top 2/3 of a cell
What effects can turbulence have on an aircraft?
- Changes in altitude
- Structural damage
- Extra stress on the airframe
- Effect depends on severity of turbulence and speed of aircraft
What hazards are associated with lightning?
- Static charge builds up in the aircraft
- Can strike aircraft flying in the clear
- Structural damage
- Catastrophic fuel inanition
- Pilots can experience flash blindness
Why do you want to penetrate a thunderstorm perpendicular?
To minimize time in the storm
What hazards to flight are associated with thunderstorms?
What would you like to do?
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