Aviation Weather Theory Exam A+
Pass Verified
What is an airmet? - Answer- Airmet Sierra - ifr and mountain obscuration
Airmet Tango - turbulence, wind shear
Airmet Zulu - icing
What is a sigmet? - Answer- severe icing
severe turbulence
volcanic ash or dust
What is a convective sigmet? - Answer- Convective SIGMET
-55 minutes past the hour and valid for 2 hours. -Line of thunderstorms
-Embedded thunderstorms
-Wide area of thunderstorms
-Severe thunderstorms characterized by wind in excess of 50 kias, hail 3/4" diameter or
greater, or tornadoes
What is diurnal temperature variation? - Answer- Diurnal temperature variation is the
difference in temperature between day and night.
What is the affect of high temperature on air density? - Answer- High temperature
reduces air density and performance
What creates local wind? - Answer- Diurnal and topographical temperature variations
create local wind
What is an effect of diurnal cooling? - Answer- Diurnal cooling is conducive to fog
What type of dangerous precipitation can be caused by a temperature inversion? -
Answer- An inversion aloft can cause rain to turn into freezing rain
What problems can result from a ground based inversion? - Answer- A ground based
inversion favors poor visibility by trapping haze, fog, and smoke at low altitudes
What is 'hg'? - Answer- Hg is the abbreviation for millibars
What is density altitude? - Answer- Density altitude - pressure altitude corrected for non-
standard temperature (the density altitude in the standard atmosphere where the air
density is the same as where you are)
How does a pressure gradient relate to wind? - Answer- The greater the difference
between pressure gradients the stronger the wind
, What slows the wind? - Answer- Friction between the wind and the surface
What is Katabatic wind? - Answer- Katabatic wind - wind blowing down an incline such
as a mountain
Which direction do sea breezes flow during the day? What about at night? - Answer-
Sea breezes flow from sea to land during the day and from land to sea at night
When the temperature dewpoint spread is less than what will you experience fog? -
Answer- When the temperature-dewpoint spread is less than 5 degrees, you may
experience fog
What is relative humidity? - Answer- How much humidity air can hold at a certain
temperature...its current saturation is the relative humidity.
What is the minimum cloud height to produce significant precipitation? - Answer- To
produce significant precipitation clouds are usually at least 4,000' tall or more
What happens to the temperature of air as it expands or contracts? - Answer- When air
expands its cool. When it compresses, it warms.
What is the lapse rate? - Answer- As air rises it cools 2 degrees celsius per 1,000'.
What is the adiabatic lapse rate? - Answer- Adiabatic means 'a condition in which heat
does not enter or leave the system concerned.' The adiabatic lapse rate could either be
the saturated adiabatic lapse rate or the dry adiabatic lapse rate. What you need to
know is the saturated adiabatic rate of cooling is slower than the dry adiabatic rate.
What are some signs of unstable air? - Answer- Thunderstorms and dust devils are a
sign of unstable air. If the temperature increases with altitude, this inversion may be a
sign of unstable air. When air near the surface is warm and moist, expect instability.
Which way does the Coriolis effect cause a hurricane to spin in the northern
hemisphere? - Answer- Counter-clockwise
What are the 4 categories of clouds? - Answer- high clouds, middle clouds, low clouds,
and clouds with extensive vertical development
What does the prefix nimbo- or nimbus- mean? - Answer- Raincloud (e.g. nimbostratus
or cumulonimbus)
What are high clouds and what altitudes do they form? - Answer- High clouds are
cirriform clouds (cirrus, cirocumulus, cirostratus) and form between 15,000-45,000'
What are middle clouds and what altitudes do they form? - Answer- altostratus,
altocumulus, and nimbostratus 6,500- 23,000'
Pass Verified
What is an airmet? - Answer- Airmet Sierra - ifr and mountain obscuration
Airmet Tango - turbulence, wind shear
Airmet Zulu - icing
What is a sigmet? - Answer- severe icing
severe turbulence
volcanic ash or dust
What is a convective sigmet? - Answer- Convective SIGMET
-55 minutes past the hour and valid for 2 hours. -Line of thunderstorms
-Embedded thunderstorms
-Wide area of thunderstorms
-Severe thunderstorms characterized by wind in excess of 50 kias, hail 3/4" diameter or
greater, or tornadoes
What is diurnal temperature variation? - Answer- Diurnal temperature variation is the
difference in temperature between day and night.
What is the affect of high temperature on air density? - Answer- High temperature
reduces air density and performance
What creates local wind? - Answer- Diurnal and topographical temperature variations
create local wind
What is an effect of diurnal cooling? - Answer- Diurnal cooling is conducive to fog
What type of dangerous precipitation can be caused by a temperature inversion? -
Answer- An inversion aloft can cause rain to turn into freezing rain
What problems can result from a ground based inversion? - Answer- A ground based
inversion favors poor visibility by trapping haze, fog, and smoke at low altitudes
What is 'hg'? - Answer- Hg is the abbreviation for millibars
What is density altitude? - Answer- Density altitude - pressure altitude corrected for non-
standard temperature (the density altitude in the standard atmosphere where the air
density is the same as where you are)
How does a pressure gradient relate to wind? - Answer- The greater the difference
between pressure gradients the stronger the wind
, What slows the wind? - Answer- Friction between the wind and the surface
What is Katabatic wind? - Answer- Katabatic wind - wind blowing down an incline such
as a mountain
Which direction do sea breezes flow during the day? What about at night? - Answer-
Sea breezes flow from sea to land during the day and from land to sea at night
When the temperature dewpoint spread is less than what will you experience fog? -
Answer- When the temperature-dewpoint spread is less than 5 degrees, you may
experience fog
What is relative humidity? - Answer- How much humidity air can hold at a certain
temperature...its current saturation is the relative humidity.
What is the minimum cloud height to produce significant precipitation? - Answer- To
produce significant precipitation clouds are usually at least 4,000' tall or more
What happens to the temperature of air as it expands or contracts? - Answer- When air
expands its cool. When it compresses, it warms.
What is the lapse rate? - Answer- As air rises it cools 2 degrees celsius per 1,000'.
What is the adiabatic lapse rate? - Answer- Adiabatic means 'a condition in which heat
does not enter or leave the system concerned.' The adiabatic lapse rate could either be
the saturated adiabatic lapse rate or the dry adiabatic lapse rate. What you need to
know is the saturated adiabatic rate of cooling is slower than the dry adiabatic rate.
What are some signs of unstable air? - Answer- Thunderstorms and dust devils are a
sign of unstable air. If the temperature increases with altitude, this inversion may be a
sign of unstable air. When air near the surface is warm and moist, expect instability.
Which way does the Coriolis effect cause a hurricane to spin in the northern
hemisphere? - Answer- Counter-clockwise
What are the 4 categories of clouds? - Answer- high clouds, middle clouds, low clouds,
and clouds with extensive vertical development
What does the prefix nimbo- or nimbus- mean? - Answer- Raincloud (e.g. nimbostratus
or cumulonimbus)
What are high clouds and what altitudes do they form? - Answer- High clouds are
cirriform clouds (cirrus, cirocumulus, cirostratus) and form between 15,000-45,000'
What are middle clouds and what altitudes do they form? - Answer- altostratus,
altocumulus, and nimbostratus 6,500- 23,000'
