Wind Shear Flashcards
Wind shear is
a) A change in wind speed and/or direction over a short distance.
b) A change in wind direction over a short distance.
c) A change in wind speed over a short direction.
A) A change in wind speed and/or direction over a short distance.
Wind shear can occur
a) Only in a vertical plane and only associated with thunderstorm gust fronts.
b) Either horizontally or vertically and is only associated with thunderstorms.
c) Either horizontally or vertically and is most often associated with strong temperature inversions or density gradients.
C) Either horizontally or vertically and is most often associated with strong temperature inversions or density gradients.
Wind shear can occur
a) Only at low altitudes.
b) At high or low altitudes.
c) Only at high altitude
B) At high or low altitudes
Common sources of low-level wind shear are
a) Frontal activity, thunderstorms, temperature inversions, and surface obstructions.
b) Temperature inversions only.
c) Thunderstorm gust fronts and microbursts.
A) Frontal activity, thunderstorms, temperature inversions, and surface obstructions.
All fronts have wind shear associated with them.
a) True
b) False.
B) False
Not all fronts have associated wind shear.
a) True.
b) False.
A) True.
Wind shear is normally a problem only with those fronts with
a) Squall line thunderstorms.
b) A frontal wave.
c) Steep wind gradients.
C) Steep wind gradients.
An indicator that a front may have associated wind shear is
a) The temperature difference across the front at the surface is 10°F (5°C) or more.
b) The front is moving at a speed of at least 30 kts.
c) All are correct.
C) All are correct
The two worst problems outside of storm penetration are windshear related. These are
a) The first gust and the downburst.
b) The first burst and the down-gust.
c) The rotor cloud and the gust front.
A) The first gust and the downburst.
The rapid shift and increase in wind just before a thunderstorm hits is the
a) First burst.
b) Gust front.
c) First gust.
C) First gust.
Gusty winds are associated with mature thunderstorms and are the result of
a) Large downdrafts striking the ground and spreading out vertically.
b) Large downdrafts striking the ground and spreading out horizontally.
c) A small column of descending air recirculating outward and upward.
B) Large downdrafts striking the ground and spreading out horizontally.
Gusty winds associated with thunderstorms can change direction by as much as 180° and reach velocities of 100 kts as far as
a) 10 miles ahead of the storm.
b) 5 miles ahead of the storm.
c) 2 miles ahead of the storm.
A) 10 miles ahead of the storm.
The gusty wind speed (associated with a thunderstorm) may increase by as much as 50% between the surface and _________, with most of the increase occurring in the first 150 feet.
a) 10,000 feet.
b) 1,500 feet.
c) 500 feet.
B) 1,500 feet.
An extremely intense, localized downdraft from a thunderstorm is referred to as
a) A gust.
b) A downburst.
c) An outflow.
B) A downburst.
The downburst (downdraft) associated with a thunderstorm exceeds 750 fpm vertical velocity at
a) 300 feet AGL
b) 1,500 feet AGL
c) 3,000 feet AGL.
A) 300 feet AGL
Some clues to the presence of a downburst from a thunderstorm is the presence of
a) Gust cloud and horizontal rain.
b) Intense lightning and hail.
c) Dust clouds, roll clouds, or intense rainfall.
C) Dust clouds, roll clouds, or intense rainfall.
A temperature inversion a few hundred feet above the ground coupled with high winds from the low- level jet stream can produce
a) Thunderstorms.
b) Significant windshear close to the ground.
c) Moderate wind gusts within 100 feet AGL.
B) Significant windshear close to the ground.
Low level windshear associate with a temperature inversion is typically the result of
a) Turbulence at the boundary between calm, cold air and a low-level warm jet stream.
b) Turbulence at the boundary between unstable warm air and a low-level cool jet stream.
c) Turbulence at the boundary between unstable warm air and a low-level warm jet stream.
A) Turbulence at the boundary between calm, cold air and a low-level warm jet stream.
Wind shear from surface obstructions is generally associated with
a) Hangars or other buildings.
b) Elevator shaft located near a helipad.
c) All are correct.
C) All are correct.
Microbursts can occur anywhere convective weather condition occur, such as
a) Thunderstorms and rain showers.
b) Virga.
c) All are correct.
C) All are correct.
Microbursts are never associated with virga.
a) True.
b) False.
B) False
The outflow region of a microburst after it reaches the ground is typically
a) 2,000 feet across.
b) 6,000 to 12,000 feet across.
c) Only a few feet in width.
B) 6,000 to 12,000 feet across.
The horizontal vortices associated with a microburst downdraft after it reaches the ground may extend
a) To 6,000 to 12,000 feet AGL
b) To over 2,000 feet AGL.
c) Just a few hundred feet above the ground.
B) To over 2,000 feet AGL.
Microburst outflows are always symmetric.
a) True.
b) False.
B) False
More than one microburst can occur in the same weather pattern.
a) True.
b) False.
A) True
After a microburst initially contact the ground, wind speed intensify for about
a) 10 minutes.
b) 15 minutes.
c) 5 minutes.
C) 5 minutes
Microbursts typically dissipate within __________ after ground contact.
a) 10 to 20 minutes
b) A half hour.
c) 5 minutes.
A) 10 to 20 minutes
Some microbursts cannot be successfully escaped with any known techniques.
a) True.
b) False.
A) True
Doppler radar wind measurements indicate that the wind speed change a pilot might expect when flying through the average microburst at its point of peak intensity is about
a) 10 kts.
b) 20 kts.
c) 45 kts.
C) 45 kts.
Evaporation of rain below a cloud base (virga) causes intense cooling of the rain shaft and subsequent
a) Cold air plunge (dry microburst formation).
b) Cold air plunge (wet microburst formation).
c) Drop of temperature (temperature inversion windshear).
A) Cold air plunge (dry microburst formation).
The best defense against windshear is to
a) Treat is as a non-event.
b) Avoid it altogether.
c) Penetrate it at 10% less than Vne.
B) Avoid it altogether.
Altimeters and the vertical speed indicator provide accurate indications during a windshear/microburst event.
a) True.
b) False.
B) False.
The potential for windshear and microburst activity exists when
a) Convective conditions are present and/or if thunderstorms appear likely.
b) Stratus clouds are present in the lower levels of the atmosphere.
c) Virga is present.
A) Convective conditions are present and/or if thunderstorms appear likely.
When flying in regions of low humidity near the surface, any convective cloud is a likely microburst producer.
a) True.
b) False.
A) True
Microburst windshear can often be identified by some obvious visual clues from the cockpit such as
a) Heavy rain or virga.
b) A ring of blowing dust or flying debris.
c) All are correct.
C) All are correct.
Microbursts are never associated with virga.
a) True.
b) False.
B) False
The outflow region of a microburst after it reaches the ground is typically
a) 2,000 feet across.
b) 6,000 to 12,000 feet across.
c) Only a few feet in width.
B) 6,000 to 12,000 feet across.
The horizontal vortices associated with a microburst downdraft after it reaches the ground may extend
a) To 6,000 to 12,000 feet AGL
b) To over 2,000 feet AGL.
c) Just a few hundred feet above the ground.
B) To over 2,000 feet AGL.
Microburst outflows are always symmetric.
a) True.
b) False.
B) False
More than one microburst can occur in the same weather pattern.
a) True.
b) False.
A) True.
After a microburst initially contact the ground, wind speed intensify for about
a) 10 minutes.
b) 15 minutes.
c) 5 minutes.
C) 5 minutes
Microbursts typically dissipate within __________ after ground contact.
a) 10 to 20 minutes
b) A half hour.
c) 5 minutes.
A) 10 to 20 minutes
Some microbursts cannot be successfully escaped with any known techniques.
a) True.
b) False.
A) True
Doppler radar wind measurements indicate that the wind speed change a pilot might expect when flying through the average microburst at its point of peak intensity is about
a) 10 kts.
b) 20 kts.
c) 45 kts.
C) 45 kts.
Evaporation of rain below a cloud base (virga) causes intense cooling of the rain shaft and subsequent
a) Cold air plunge (dry microburst formation).
b) Cold air plunge (wet microburst formation).
c) Drop of temperature (temperature inversion windshear).
A) Cold air plunge (dry microburst formation).
The best defense against windshear is to
a) Treat is as a non-event.
b) Avoid it altogether.
c) Penetrate it at 10% less than Vne.
B) Avoid it altogether.
Altimeters and the vertical speed indicator provide accurate indications during a windshear/microburst event.
a) True.
b) False.
B) False.
The potential for windshear and microburst activity exists when
a) Convective conditions are present and/or if thunderstorms appear likely.
b) Stratus clouds are present in the lower levels of the atmosphere.
c) Virga is present.
A) Convective conditions are present and/or if thunderstorms appear likely.
When flying in regions of low humidity near the surface, any convective cloud is a likely microburst producer.
a) True.
b) False.
A) True.
Microburst windshear can often be identified by some obvious visual clues from the cockpit such as
a) Heavy rain or virga.
b) A ring of blowing dust or flying debris.
c) All are correct.
C) All are correct.
