7: (110) Aviation Weather Flashcards
Which combination of weather-producing variables would likely result in cumuliform-type clouds, good visibility, and showery rain?
Unstable moist air and Orographic lifting.
Which is a characteristic typical of a stable air mass?
Continuous precipitation
Temperature and radiation variations over land with a clear sky typically lead to…
minimum temperature occurring after sunrise.
The wind system associated with a low-pressure area in the Northern Hemisphere is…
a cyclone and is caused by Coriolis force.
The minimum vertical wind shear value critical for probable moderate or greater turbulence is…
5 knots per 1,000 feet.
Fog produced by frontal activity is a result of saturation due to…
evaporation of precipitation.
What causes wind?
Pressure differences.
Convective currents are most active on warm summer afternoons when winds are…
light
Which in-flight hazard is most commonly associated with warm fronts?
Precipitation-induced fog.
Which is true regarding actual air temperature and dew point temperature spread? The temperature spread…
decreases as relative humidity increases
Which is true with respect to a high- or low-pressure system?
A high-pressure area or ridge is an area of descending air.
Which would decrease the stability of an air mass?
Warming from below.
There is a high pressure system that is located south of your planned route in the Northern Hemisphere on a west to east cross-country flight. To take advantage of favorable winds, you would plan your route…
on the north side of the high pressure area.
Which statement is true regarding squall lines?
They are nonfrontal and often contain severe, steady-state thunderstorms
The conditions most favorable to wave formation over mountainous areas are a layer of…
stable air at mountaintop altitude and a wind of at least 20 knots blowing across the ridge.
Ice pellets encountered during flight normally are evidence that…
a warm front is about to pass.
Why does the wind have a tendency to flow parallel to the isobars above the friction level?
Coriolis force tends to counterbalance the horizontal pressure gradient.
What minimum distance should exist BETWEEN intense radar echoes before any attempt is made to fly between these thunderstorms?
40 Miles
What are the standard temperature and pressure values for sea level?
15°C and 29.92” Hg.
A situation most conducive to the formation of advection fog is…
an air mass moving inland from the coastline during the winter.
From which measurement of the atmosphere can stability be determined?
The ambient lapse rate.
Virga is best described as
streamers of precipitation trailing beneath clouds which evaporate before reaching the ground.
A pilot reporting turbulence that momentarily causes slight, erratic changes in altitude and/or attitude should report it as…
light turbulence.
The wind system associated with a low-pressure area in the Northern Hemisphere is…
a cyclone and is caused by Coriolis force.
Which is true regarding the development of convective circulation?
Cool air must sink to force the warm air upward.
One of the most dangerous features of mountain waves is the turbulent areas in and…
below rotor clouds.
The general circulation of air associated with a high-pressure area in the Northern Hemisphere is…
outward, downward, and clockwise.
What is the approximate base of the cumulus clouds if the temperature at 2,000 feet MSL is 10°C and the dew point is 1°C?
10-1 = 9 9/2.5 = 3.6 = 3600 AGL + 2000 MSL = 5600 MSL ~6000 ft MSL
When turbulence causes changes in altitude and/or attitude, but aircraft control remains positive, that should be reported as…
moderate.
