1. Precipitation, Air Masses, and Fronts
Current Weather
Finish Precipitation
Air Masses  
Fronts
For Next Class: Read Chapter 7 (pp )
Reminder: Exam I next Friday! Review sheet is posted

2. Moisture Droplets
Figure 7.20

3. Raindrop and Snowflake Formation
Figure 7.21

4. Saturation Vapor Pressure
Figure 7.12

5. Favorable conditions for freezing rain
Temperature conditions required for formation of frozen, freezing, and liquid forms of precipitation
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6. Cloud Types and Identification
Figure 7.22

7. Atmospheric Lifting Mechanisms
Figure 8.6

8. Orographic Precipitation
Figure 8.9

9. Orographic Patterns
Figure 8.10

12. Average Annual Precipitation

13. What is Rime Ice? 13

14. Rime Ice
A coating of tiny, white, ice particles caused by the rapid freezing of supercooled water droplets on impact with an object.

15. Rime Ice on Mt. Mitchell 15

16. Rime Ice on Beech Mountain

17. Heavy Rime Icing on Mt. Washington17

18. 18

19. Rime Icing on
Grandfather
Mountain

22. Snow Particle Photomicroscopy
Graupel

23. Snow Particle Photomicroscopy

24. Air Masses
What are the major air mass types and source regions?

25. Air Masses Classified as Four basic types
Cold (polar, abbreviated as P) or warm (tropical or T)
Dry (continental or c) or humid (maritime or m)
Four basic types
Cold and dry, continental polar (cP)
Cold and humid, maritime polar (mP)
Warm and dry, continental tropical (cT)
Warm and humid, maritime tropical (mT)
Fifth type, arctic (A) air, is dry like continental polar air but colder
© AMS

26. © AMS

27. Air Masses
Also differ in stability
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28. Fronts
Narrow zone of transition between air masses that differ in density
Density differences usually due to temperature contrasts
Warm and cold fronts
Frontogenesis: fronts form or grow stronger
Frontolysis: fronts weaken
© AMS