Chapter 8Weather

  Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharles E. Thomsen

Weather Air Masses  

Atmospheric Lifting Mechanisms  

Fronts  

Air Masses

Figure 8.2

Lake Effect

Snowbelts

Figure 8.5

Atmospheric Lifting Mechanisms Convergent Lifting  

Convectional Lifting  

Orographic Lifting  

Frontal Lifting (Cold and Warm Fronts)  

Atmospheric Lifting Mechanisms 

Figure 8.6

Figure 6.11

Local Heating and Convection

Figure 8.7

Convection over Florida

Figure 8.8

Orographic Precipitation

Figure 8.9

Orographic Patterns

Figure 8.10

Frontal LiftingFronts: named after attacking air mass

Remember: cold air is denser, heavier

Cold FrontsCold air forces warm air aloft

400 km wide (250 mi)

Warm FrontsWarm air moves up and over cold air

1000 km wide (600 mi)

Frontal LiftingBoth cold and warm fronts cause air to be uplifted.

This causes adiabatic cooling, low pressure, cloud development, rainfall.

Keep in mind the properties of each type of air mass and their changes as the front passes.

Frontal LiftingThe BIG FIVE! Know how these change:

Humidity

Temperature

Pressure

Wind direction/speed

Cloud types

Cold front: blue triangles

Warm front: red/orange half circles

Cold Front

Figure 8.11

Cold Frontand

Squall Line

Warm Front

Figure 8.13