Term
What causes variations in altimeter settings between weather reporting points? |
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Definition
Unequal heating of the earth's surface.
AW |
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Term
The wind at 5,000 ft AGL is southwesterly while the surface wind is southerly. This difference in direction is primarily due to |
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Definition
friction between the wind and the surface.
AW |
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Term
Convective circulation patterns associated with sea breezes are caused by |
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Definition
cool, dense air moving inland from over the water.
AW |
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Term
How will frost on the wings of an airplane affect takeoff performance? |
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Definition
Frost will disrupt the smooth flow of air over the wing, adversely affecting its lifting capability.
PHB |
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Term
Every physical process of weather is accompanied by, or is the result of, a |
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Definition
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Term
A temperature inversion would most likely result in which weather condition? |
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Definition
An increase in temperature as altitude is increased.
AW |
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Term
The most frequent type of ground or surface-based temperature inversion is that which is produced by |
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Definition
terrestrial radiation on a clear, relatively still night.
AW |
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Term
Which weather conditions should be expected beneath a low-level temperature inversion layer when the relative humidity is high? |
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Definition
Smooth air, poor visibility, fog, haze, or low clouds.
AW |
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Term
What is meant by the term "dewpoint"? |
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Definition
The temperature at which air must be cooled to become saturated.
AW |
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Term
The amount of water vapor which air can hold depends on the |
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Definition
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Term
Clouds, fog, or dew will always form when |
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Definition
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Term
What are the processes by which moisture is added to unsaturated air? |
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Definition
Evaporation and condensation.
AW |
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Term
Which conditions result in the formation of frost? |
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Definition
The temperature of the collecting surface is at or below the dewpoint of the adjacent air and the dewpoint is below freezing.
AW |
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Term
The presence of ice pellets at the surface is evidence that there |
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Definition
is a temperature inversion with freezing rain at a higher altitude.
AW |
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Term
What measurement can be used to determine the stability of the atmosphere? |
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Definition
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Term
What would decrease the stability of an air mass? |
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Definition
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Term
What is a characteristic of stable air? |
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Definition
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Term
Moist, stable air flowing upslope can be expected to |
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Definition
produce stratus type clouds.
AW |
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Term
IF an unstable air mass is forced upward, what type clouds can be expected? |
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Definition
Clouds with considerable vertical development and associated turbulence.
AW |
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Term
What feature is associated with a temperature inversion? |
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Definition
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Term
What is the approximate base of the cumulus clouds if the surface air temperature at 1,000 ft MSL is 70F and the dewpoint is 48F? |
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Definition
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Term
At approximately what altitude above the surface would the pilot expect the base of cumuliform clouds if the surface air temperature is 82F and the dewpoint is 38F? |
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Definition
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Term
What are characteristics of a moist, unstable air mass? |
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Definition
Cumuliform clouds and showery precipitation.
AW |
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Term
What are characteristics of unstable air? |
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Definition
Turbulence and good surface visibility.
AW |
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Term
A stable air mass is most likely to have which characteristic? |
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Definition
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Term
The suffix "nimbus," used in naming clouds, means |
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Definition
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Term
Clouds are divided into four families according to their |
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Definition
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Term
The boundary between two different air masses is referred to as a |
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Definition
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Term
One of the most easily recognized discontinuities across a front is |
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Definition
a change in temperature.
AW |
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Term
One weather phenomenon which will always occur when flying across a front is a change in the |
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Definition
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Term
Steady precipitation preceding a front is an indication of |
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Definition
stratiform clouds with little or no turbulence.
AW |
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Term
What situation is most conducive to the formation of radiation fog? |
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Definition
Warm, moise air over low, flatland areas on clear, calm nights.
AW |
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Term
If the temperature/dewpoint spread is small and decreasing, and the temperature is 62F, what type weather is most likely to develop? |
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Definition
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Term
In which situation is advection fog most likely to form? |
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Definition
An air mass moving inland from the coast in winter.
AW |
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Term
What types of fog depend upon wind in order to exist? |
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Definition
Advection fog and upslope fog.
AW |
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Term
Low-level turbulence can occur and icing can become hazardous in which type of fog? |
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Definition
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Term
An almond or lens-shaped cloud which appears stationary, but which may contain winds of 50 knots or more, is referred to as |
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Definition
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Term
Crests of standing mountain waves may be marked by stationary, lens-shaped clouds known as |
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Definition
standing lenticular clouds.
AW |
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Term
What clouds have the greatest turbulence? |
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Definition
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Term
What cloud types would indicate convective turbulence? |
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Definition
Towering cumulus clouds.
AW |
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Term
Possible mountain wave turbulence could be anticipated when winds of 40 knots or greater blow |
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Definition
across a mountain ridge, and the air is stable.
AW |
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Term
Where does wind shear occur? |
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Definition
At all altitudes, in all directions.
AW |
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Term
When may hazardous wind shear be expected? |
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Definition
In areas of low-level temperature inversion, frontal zones, and celar air turbulence.
AW |
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Term
A pilot can expected a wind-shear zone in a temperature inversion whenever the windspeed at 2,000 to 4,000 feet above the surface is at least |
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Definition
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Term
One in-flight condition necessary for structural icing to form is |
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Definition
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Term
In which environment is aircraft structural ice most likely to have the highest accumulation rate? |
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Definition
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Term
Why is frost considered hazardous to flight? |
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Definition
Frost spoils the smooth flow of air over the wings, thereby decreasing lifting capability.
AW |
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Term
How does frost affect the lifting surfaces of an airplane on takeoff? |
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Definition
Frost may prevent the airplane from becoming airborne at normal takeoff speed.
AW |
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Term
The conditions necessary for the formation of cumulonimbus clouds are a lifting action and |
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Definition
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Term
What feature is normally associated with the cumulus stage of a thunderstorm? |
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Definition
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Term
Which weather phenomenon signals the beginning of the mature stage of a thunderstorm? |
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Definition
Precipitation beginning to fall.
AW |
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Term
What conditions are necessary for the formation of thunderstorms? |
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Definition
High humidity, lifting force, and unstable conditions.
AW |
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Term
During the life cycle of a thunderstorm, which stage is characterized predominately by downdrafts? |
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Definition
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Term
Thunderstorms reach their greatest intensity during the |
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Definition
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Term
Thunderstorms which generally produce the most intense hazard to aircraft are |
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Definition
squall line thunderstorms.
AW |
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Term
A nonfrontal, narrow band of active thunderstorms that often develop ahead of a cold front is known as a |
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Definition
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Term
If there is thunderstorm activity in the vicinity of an airport at which you plan to land, which hazardous atmospheric phenomenon might be expected on the landing approach? |
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Definition
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Term
Upon encountering severe turbulence, which flight condition should the pilot attempt to maintain? |
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Definition
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Term
Which weather phenomenon is always associated with a thunderstorm? |
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Definition
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Term
Wingtip vortices are created only when an aircraft is |
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Definition
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Term
The greatest vortex strength occurs when the generating aircraft is |
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Definition
heavy, clean, and slow
PHB |
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Term
Wingtip vortices created by large aircraft tend to |
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Definition
sink below the aircraft generating turbulence.
PHB |
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Term
When taking off or landing at an airport where heavy aircraft are operating, one should be particularly alert to the hazards of wingtip vortices because this turbulence tends to |
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Definition
sink into the flightpath of aircraft operating below the aircraft generating the turbulence.
PHB |
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Term
The wind condition that requires maximum caution when avoiding wake turbulence on landing is a |
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Definition
light, quartering tailwind.
PHB |
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Term
When landing behind a large aircraft, the pilot should avoid wake turbulence by staying |
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Definition
above the large aircraft's final approach path and landing beyond the large aircraft's touchdown point.
PHB |
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Term
When departing behind a heavy aircraft, the pilot should avoid wake turbulence by maneuvering the aircraft |
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Definition
above and upwind from the heavy aircraft.
PHB |
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Term
When landing behind a large aircraft, which procedure should be followed for a vortex avoidance? |
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Definition
Stay above its final approach flightpath all the way to touchdown. |
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Term
How does the wake turbulence vortex circulate around each wingtip? |
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Definition
Outward, upward, and around each tip.
PHB |
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