Chapter 8 cover

air masses

An air mass is a large body of air that has similar An air mass is a large body of air that has similar temperature and moisture properties throughout. temperature and moisture properties throughout.

The best source regions for air masses are large The best source regions for air masses are large flat areas where air can be stagnant long enough flat areas where air can be stagnant long enough to take on the characteristics of the surface below.to take on the characteristics of the surface below.

Figure 8.1

temperaturetemperatureP-PolarP-Polar

A-ArcticA-Arctic

T-TropicalT-Tropical

humidityhumidity

m-Maritime-wetm-Maritime-wet

c-Continental-dryc-Continental-dry

classifying air massesclassifying air masses

air masses

Continental Polar Air MassesContinental Polar Air Masses

cold temperatures and little moisturecold temperatures and little moisture

a map of surface observations and the leading edge of a large arctic air mass blanketing much of the United States has been highlighted by the blue line.

The center of this air mass is a high pressure center located in northern Montana (indicated by the blue "H")

Continental Polar AirContinental Polar Air

Maritime Tropical Air MassesMaritime Tropical Air Masses

warm temperatures and rich in moisturewarm temperatures and rich in moisture

Maritime Tropical AirMaritime Tropical Air

a map of surface observations and the leading edge of a tropical air mass surging northward into the Ohio Valley has been highlighted in red.

Southerly winds behind the boundary signify the continued northward transport of warm moist air

k-coldk-coldw-warmw-warm

air mass modificationair mass modification

cP-wcP-w

fronts

cold front

Figure 8.2

Figure 8.3

fronts

warm front

Figure 8.4

fronts

fronts

occluded fronts

mid-latitude cyclone

formation of an occlusion

mature cyclone

partial occlusion

occlusion

life of a midlatitiude

cyclone

Figure 8.8

Figure 8.9

Figure 8A

Figure 8.10

Figure 8.7