1. An Introduction to Physical Geography
Chapter 8 Weather
Geosystems 6e
An Introduction to Physical Geography
Robert W. Christopherson
Charles E. Thomsen

2. Weather
Air Masses  
Atmospheric Lifting Mechanisms  
Fronts  

3. Air Masses
Figure 8.2

4. Lake Effect Snowbelts
Figure 8.5

5. Atmospheric Lifting Mechanisms
Convergent Lifting  
Convectional Lifting  
Orographic Lifting  
Frontal Lifting (Cold and Warm Fronts)  

6. Atmospheric Lifting Mechanisms
Figure 8.6

7. Figure 6.11

8. Local Heating and Convection
Figure 8.7

9. Convection over Florida
Figure 8.8

10. Orographic Precipitation
Figure 8.9

11. Orographic Patterns
Figure 8.10

12. Frontal Lifting Fronts: named after attacking air mass
Remember: cold air is denser, heavier
Cold Fronts
Cold air forces warm air aloft
400 km wide (250 mi)
Warm Fronts
Warm air moves up and over cold air
1000 km wide (600 mi)

13. Frontal Lifting Both 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.

14. Frontal Lifting The BIG FIVE! Know how these change:
Humidity
Temperature
Pressure
Wind direction/speed
Cloud types
Cold front: blue triangles
Warm front: red/orange half circles

15. Cold Front
Figure 8.11

17. Cold Front and Squall Line

18. Warm Front
Figure 8.13