Weather Theory Flashcards
What region of atmosphere does most weather occur?
(AC 00-6) Troposphere: Surface to 36,000’
What are the standard temperature and pressure values for sea level?
(FAA-H-8083-25) 15°C (59°F) and 29.92” Hg (1013.2 mb)
What does the spacing of the isobars represent?
(AC 00-6) Spacing defines how steep or shallow pressure gradient is. Close = steep; Far = shallow
What does Dew Point mean?
(AC 00-6) Dew point is the temperature to which a sample of air must be cooled to attain the state of saturation.
How does fog form?
(AC 00-6) Fog forms when the temperature and dewpoint of the air become identical.
What factor determines the type and vertical extent of clouds?
(AC 00-6) Stability of atmosphere
What is the difference between a stable and unstable atmosphere?
(AC 00-6) Stabile atmosphere resists vertical motion and an unstable atmosphere has large vertical motion.
How is the stability of the atmosphere determined?
(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’
What conditions are associated with a stable atmosphere?
(AC 00-6) Stratiform clouds, smooth turbulence, steady precipitation and fair to poor visibility
What conditions are associated with an unstable atmosphere?
(AC 00-6) Cumuliform clouds, rough turbulence, showery precipitation, good visibility
What is the direction of airflow around a high pressure system in Northern Hemisphere?
(AC 00-6) High pressure is outward, downward, and clockwise
What is the direction of airflow around a low pressure system in Northern Hemisphere?
(AC 00-6) Low pressure is inward, upward, and counterclockwise
If your route of flight takes you toward a low-pressure system, in general what kind of weather can you expect?
(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.
If your route of flight takes you toward a high-pressure system, in general what kind of weather can you expect?
(AC 00-6) A high-pressure system is an area of descending air, which tends to favor dissipation of cloudiness and good weather.
What is a cold front?
(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.
What is an Occluded Front
(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.
What is a Warm Front
(AC 00-6, FAA-H-8083-25B) Warm front occurs when a mass of warm contacts and flows over a colder air mass
What is a Stationary Front
(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.
What are the general characteristics of the weather associated with a cold front
(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.
What are the general characteristics of the weather associated with a warm front
(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.
What is a Trough?
(AC 00-6, FAA-H-8083-25B) Elongated area of low pressure with rising air and bad weather
What is a Ridge?
(AC 00-6, FAA-H-8083-25B) Elongated area of high pressure with descending air and good weather
