Air Masses + Pressure Systems Flashcards
What are the two classification of Air masses?
Polar
Tropical
What are sub categories of air masses?
Continental
Maritime
What Air mass produces
High temp/DP/Humidity
Warm moist and hazy with broken cloud. Advection fog over coast and sea (summer)
Warm and Moist with low cloud or fog + drizzle (winter)
Warm and moist with low cloud or fog and drizzle?
Tropical maritime
What Air mass produces
High temp, low DP/Humidity
Warm + dry overland with little cloud but often hazy due to dust particles from air mass (summer)
Tropical continental
What Air mass produces
Low temp, High DP/ Humidity
Cool with showers, thunderstorms near the coast and clear inland. Good visibility except in precipitation (summer)
Surface cooling over the land and becomes stable. Possible layer cloud/fog over night (winter)
Polar maritime
What Air mass causes
Low temp/DP/Humidity
Rain or snow showers but often cold and clear inland (winter)
Polar continental
What are two other Air masses effecting Europe?
Equatorial- moist and unstable
Continental Arctic - very cold, dry and stable.
An area of high pressure is known as
An anticyclone
An area of low pressure is known as a
Depression/cyclone
How is an anticyclone formed?
Rising surface pressure causes divergence. Draws cold air down from above.
List the different types of depressions
- frontal
- Instability
- secondary
- orographic
- thermal
- trough
How is a depression formed?
Air rises and cools Adiabatically. If it is sufficiently moist will give thick cloud and precipitation
What is a ridge?
An area of high pressure which elongates. Shown by a zig zag line on a chart
What is a trough?
An elongated area of low pressure.
Where does polar continental air mass come from?
Siberia
Where does Polar Maritime Air mass come from?
North Atlantic
Where does the Tropical Continental Air mass come from?
North Africa (Northern Hemisphere only)
Where does the Tropical Maritime Air mass come from?
The Azores + South Atlantic Ocean
What cause an anti-cyclone gloom?
A weak inversion near the surface.
May occur under a layer of Strato cumulus (Sc)
