Air Masses

Where do they form?

Source region; high pressure zone and associated air subsidence; upper-level convergence of cold, dry air; big uniform bodies of water; over areas that are similar

How do they change when they move?

Wind moves them as they move over different areas then where they formed; temperature and moisture characteristics begin to change with movement.

change when move? (Speed of motion) =

more rapid change (faster and air mass moves the faster it will change)

change when move? (Distance traveled) =

more change (further the air mass travels the more it changes)

change when move? (Dissimilarity of the areas traveled over)

(EX: cold, dry air moves over Gulf of Mexico, will make it turn humid, wet)

Large size

usually flat, with homogenous temperature and moisture characteristics (EX: cold and dry or warm and wet)

Light upper-level winds

allows air to remain in a source region long enough to take on the characteristics of the source region

High pressure zone

consistent with global circulation and air subsidence

Moisture

indicated by surface nature of source region (lower case)

continental

dry (c) (formed over land)

maritime

wet (m) (formed over oceans)

Temperature

indicated by latitudinal zone of formation (upper case)

Polar = cold (P)

Arctic

extremely cold (A)

Tropical

warm (T)

Equatorial

extremely warm (E)

Which air masses impact the U.S.?

Continental Polar (cP)

Continental Arctic (cA)

Continental Tropical (cT)

Maritime Polar (mP)

Maritime Tropical (mT)

Which air masses impact Texas?

Maritime Tropical (mT) - Gulf

Continental Tropical (cT) - northern Mexico