Download AIR MASSES AND FRONTS

AIR MASSES
AND FRONTS
Air Masses
Maritime Tropical (mT)
Warm, moist, usually
unstable.
Maritime Polar (mP)
Cool, moist, unstable.
Continental Tropical (cT) Hot, dry, stable air aloft;
unstable surface air.
Continental Polar (cP)
Cold, dry, stable.
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P. Samson - University of Michigan
AIR MASSES
•  North America cP
–  Source region: Northern Canada, Alaska
–  Dry, cold, stable
–  Extremely cold associated with upper-level
winds typically with a strong north-south
(meridional) trajectory.
–  Air mass will be modified by the land surface
over which it travels
©201
P. Samson - University of Michigan
AIR MASSES
•  North American mP
–  Source region: North Pacific, North Atlantic
–  Cool, moist, unstable
•  North American mT
–  Source region: Gulf of Mexico, Caribbean,
Southeast Pacific
–  Wet, warm, unstable
–  Pineapple Express, Bermuda High
Fig. 9.7, p. 245
Stepped Art
AIR MASSES
•  North American cT
–  Source region: Southwest United States,
Mexican Plateau
–  Hot, dry, stable
Fig. 9.14, p. 249
Characteristics of Fronts
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P. Samson - University of Michigan
FRONTS
•  Stationary
–  Front with no movement
–  Alternating red and blue line with blue triangles
and red semi-circles
–  Winds parallel but opposite direction
–  Variable weather
FRONTS
•  Cold
–  Cold, dry stable air replaces warm, moist
unstable air
–  Blue line with blue triangles
–  Clouds of vertical development
–  Thunderstorms, squall lines
–  Back door vs. strong
Characteristics of Cold Fronts
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P. Samson - University of Michigan
Characteristics of Cold Fronts
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P. Samson - University of Michigan
Fig. 9.19, p. 254
Fig. 9.22, p. 256
FRONTS
•  Warm
–  Warm, moist unstable air overrides cold, dry
stable air
–  Red line with red semi-circles
–  Horizontal cloud development with steady rain
•  Dry Line
–  Not a cold or warm front but a narrow
boundary of steep change in dew point
Characteristics of Warm Fronts
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P. Samson - University of Michigan
Characteristics of Warm Fronts
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P. Samson - University of Michigan
Occluded Front
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P. Samson - University of Michigan
Characteristics of Occluded Fronts
Cold Occlusion
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P. Samson - University of Michigan
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P. Samson - University of Michigan
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P. Samson - University of Michigan
Characteristics of Occluded Fronts
Warm Occlusion
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P. Samson - University of Michigan
How to Locate a Front
1. 
Change in temperature
2. 
Change in dew point temperature
3. 
Change in wind direction
4. 
Occurrence of precipitation
5. 
Occurrence of cloud cover
6. 
Local change in pressure
©201
P. Samson - University of Michigan