Aviation Weather Exam Study Guide
(IERW) (2024) || Questions & Answers
(Graded A)
The lowest layer of the atmosphere is the ____ and is approximately ____ feet at the equator and ____ feet at the poles. - ANSWER - troposphere
60,000'
25,000'
What is the difference between dry air and natural air? - ANSWER - natural air contains water vapor and condensation nuclei
Name the two major conditions affecting atmospheric circulation: - ANSWER - uneven heating
rotation of the earth
Name one semi-permanent pressure (air mass) system that causes weather over the United States. - ANSWER - North American High (CP) or Bermuda High (MT) or Siberian High (MP)
One method of heat transfer is radiation. Define radiation: - ANSWER - transfer of heat by electromagnetic waves
What is the difference between convection and advection? - ANSWER - convection is the transfer of heat vertically via a gas; advection is the transfer of heat horizontally via the wind (gas).
What is the definition of an air mass? - ANSWER - a large body of air whose physical properties (temperature and moisture) are horizontally uniform
What does the air mass classification code "c" indicate? - ANSWER - the air mass was formed over land (continental)
What is the source region and temperature/moisture content of an mP air mass? - ANSWER - Maritime Polar (Atlantic or Pacific Oceans), cold/moist
Is an air mass designated cPk warmer or colder than the surface? - ANSWER - colder
Is a cPk air mass stable or unstable? - ANSWER - unstable
Define OLR: - ANSWER - observed lapse rate, the actual change in the air temperature with an increase in altitude If the temperature is increasing with altitude it is called an ____; Two types of these are ____ and ____. - ANSWER - inversion, nocturnal, frontal
Polar air masses normally move in a ____ direction and tropical air masses in a ____ direction in the northern hemisphere. - ANSWER - southerly, northerly
Standard mean sea level pressure in "mb" millibars is ____; in inches of mercury "Hg" ____. - ANSWER - 1013.2 29.92
Define an isobar and its spacing on a surface analysis chart: - ANSWER - a line connecting points of equal barometric pressure corrected to MSL spaced 4mb apart
The force that starts the wind moving is the ____. - ANSWER - pressure gradient
Pressure gradient forces always act from ____ pressure to ____ pressure. - ANSWER -
high, low
How are isobars used to indicate strong or weak gradient forces? - ANSWER - closely spaced isobars indicate a strong/steep gradient; widely spaced isobars indicate a weak/flat gradient
In what direction does the wind flow around a high pressure area in the northern hemisphere? - ANSWER - clockwise
How does the wind flow in relation to the isobars above the friction level (above 2,000' AGL) - ANSWER - parallel
What force modifies gradient force and causes the wind to flow parallel to the isobars above 2,000'? - ANSWER - coriolis
What force is evident at the surface that causes the wind to flow across the isobars? - ANSWER - friction
On the following diagrams draw the gradient and surface winds. - ANSWER - high pressure turns clockwise
low pressure turns counter-clockwise
Near the center of a high, the air tends to ____ and in a low it tends to ____. - ANSWER
- sink, rise
State Buys Ballots Law: - ANSWER - in the northern hemisphere, with your back to the wind the are of lower pressure will be to your left
You are crabbing left to correct for a left crosswind, where is the area of lower pressure? - ANSWER - ahead of you
(IERW) (2024) || Questions & Answers
(Graded A)
The lowest layer of the atmosphere is the ____ and is approximately ____ feet at the equator and ____ feet at the poles. - ANSWER - troposphere
60,000'
25,000'
What is the difference between dry air and natural air? - ANSWER - natural air contains water vapor and condensation nuclei
Name the two major conditions affecting atmospheric circulation: - ANSWER - uneven heating
rotation of the earth
Name one semi-permanent pressure (air mass) system that causes weather over the United States. - ANSWER - North American High (CP) or Bermuda High (MT) or Siberian High (MP)
One method of heat transfer is radiation. Define radiation: - ANSWER - transfer of heat by electromagnetic waves
What is the difference between convection and advection? - ANSWER - convection is the transfer of heat vertically via a gas; advection is the transfer of heat horizontally via the wind (gas).
What is the definition of an air mass? - ANSWER - a large body of air whose physical properties (temperature and moisture) are horizontally uniform
What does the air mass classification code "c" indicate? - ANSWER - the air mass was formed over land (continental)
What is the source region and temperature/moisture content of an mP air mass? - ANSWER - Maritime Polar (Atlantic or Pacific Oceans), cold/moist
Is an air mass designated cPk warmer or colder than the surface? - ANSWER - colder
Is a cPk air mass stable or unstable? - ANSWER - unstable
Define OLR: - ANSWER - observed lapse rate, the actual change in the air temperature with an increase in altitude If the temperature is increasing with altitude it is called an ____; Two types of these are ____ and ____. - ANSWER - inversion, nocturnal, frontal
Polar air masses normally move in a ____ direction and tropical air masses in a ____ direction in the northern hemisphere. - ANSWER - southerly, northerly
Standard mean sea level pressure in "mb" millibars is ____; in inches of mercury "Hg" ____. - ANSWER - 1013.2 29.92
Define an isobar and its spacing on a surface analysis chart: - ANSWER - a line connecting points of equal barometric pressure corrected to MSL spaced 4mb apart
The force that starts the wind moving is the ____. - ANSWER - pressure gradient
Pressure gradient forces always act from ____ pressure to ____ pressure. - ANSWER -
high, low
How are isobars used to indicate strong or weak gradient forces? - ANSWER - closely spaced isobars indicate a strong/steep gradient; widely spaced isobars indicate a weak/flat gradient
In what direction does the wind flow around a high pressure area in the northern hemisphere? - ANSWER - clockwise
How does the wind flow in relation to the isobars above the friction level (above 2,000' AGL) - ANSWER - parallel
What force modifies gradient force and causes the wind to flow parallel to the isobars above 2,000'? - ANSWER - coriolis
What force is evident at the surface that causes the wind to flow across the isobars? - ANSWER - friction
On the following diagrams draw the gradient and surface winds. - ANSWER - high pressure turns clockwise
low pressure turns counter-clockwise
Near the center of a high, the air tends to ____ and in a low it tends to ____. - ANSWER
- sink, rise
State Buys Ballots Law: - ANSWER - in the northern hemisphere, with your back to the wind the are of lower pressure will be to your left
You are crabbing left to correct for a left crosswind, where is the area of lower pressure? - ANSWER - ahead of you
