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Three requirements for a thunderstorm:
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
: 1/3 distance from ground to cloud base
: lower 1/3 of storm; below freezing level
What is the procedure if you must penetrate a thunderstorm?
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
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
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?