Weather Theory

Question 1

What region of atmosphere does most weather occur?

Answer 1

(AC 00-6) Troposphere: Surface to 36,000’

Question 2

What are the standard temperature and pressure values for sea level?

Answer 2

(FAA-H-8083-25) 15°C (59°F) and 29.92” Hg (1013.2 mb)

Question 3

What does the spacing of the isobars represent?

Answer 3

(AC 00-6) Spacing defines how steep or shallow pressure gradient is. Close = steep; Far = shallow

Question 4

What does Dew Point mean?

Answer 4

(AC 00-6) Dew point is the temperature to which a sample of air must be cooled to attain the state of saturation.

Question 5

How does fog form?

Answer 5

(AC 00-6) Fog forms when the temperature and dewpoint of the air become identical.

Question 6

What factor determines the type and vertical extent of clouds?

Answer 6

(AC 00-6) Stability of atmosphere

Question 7

What is the difference between a stable and unstable atmosphere?

Answer 7

(AC 00-6) Stabile atmosphere resists vertical motion and an unstable atmosphere has large vertical motion.

Question 8

How is the stability of the atmosphere determined?

Answer 8

(AC 00-6) Stability is determined by the temperature change with altitude. Lapse rate of stable air is 2°C (3.5°F) per 1000’

Question 9

What conditions are associated with a stable atmosphere?

Answer 9

(AC 00-6) Stratiform clouds, smooth turbulence, steady precipitation and fair to poor visibility

Question 10

What conditions are associated with an unstable atmosphere?

Answer 10

(AC 00-6) Cumuliform clouds, rough turbulence, showery precipitation, good visibility

Question 11

What is the direction of airflow around a high pressure system in Northern Hemisphere?

Answer 11

(AC 00-6) High pressure is outward, downward, and clockwise

Question 12

What is the direction of airflow around a low pressure system in Northern Hemisphere?

Answer 12

(AC 00-6) Low pressure is inward, upward, and counterclockwise

Question 13

If your route of flight takes you toward a low-pressure system, in general what kind of weather can you expect?

Answer 13

(AC 00-6) A low-pressure system is characterized by rising air, which is conducive to cloudiness, precipitation and bad weather. Winds will be from the left.

Question 14

If your route of flight takes you toward a high-pressure system, in general what kind of weather can you expect?

Answer 14

(AC 00-6) A high-pressure system is an area of descending air, which tends to favor dissipation of cloudiness and good weather.

Question 15

What is a cold front?

Answer 15

(AC 00-6, FAA-H-8083-25B) A cold front occurs when a mass of cold, dense, and stable air advances and replaces a body of warm air.

Question 16

What is an Occluded Front

Answer 16

(AC 00-6, FAA-H-8083-25B) An occluded front occurs when a fast moving cold front catches up with a slow moving warm front. Two types: cold and warm.

Question 17

What is a Warm Front

Answer 17

(AC 00-6, FAA-H-8083-25B) Warm front occurs when a mass of warm contacts and flows over a colder air mass

Question 18

What is a Stationary Front

Answer 18

(AC 00-6, FAA-H-8083-25B) When two air masses are relatively equal, the boundary or front that separates them remains stationary and influences the local weather for days. The weather is typically a mixture of both warm and cold fronts.

Question 19

What are the general characteristics of the weather associated with a cold front

Answer 19

(FAA-H-8083-25B) As the cold front passes, expected weather can include towering cumulus or cumulonimbus, heavy rain accompanied by lightning, thunder and/or hail; tornadoes possible; during passage, poor visibility, winds variable and gusting; temperature/dew point and barometric pressure drop rapidly.

Question 20

What are the general characteristics of the weather associated with a warm front

Answer 20

(FAA-H-8083-25B) As the warm front passes, expected weather can include stratiform clouds, drizzle, low ceilings and poor visibility; variable winds; rise in temperature.

Question 21

What is a Trough?

Answer 21

(AC 00-6, FAA-H-8083-25B) Elongated area of low pressure with rising air and bad weather

Question 22

What is a Ridge?

Answer 22

(AC 00-6, FAA-H-8083-25B) Elongated area of high pressure with descending air and good weather