1. Air Masses and Weather Fronts

2. Air Masses
Air mass – large body of air that takes on the characteristics of the area of which it forms (source region)
Over land – drier
Over water – more humid
Also takes on temperature of source region

3. Air Masses - Origins
What do you think Air Mass #1 would be like in April? Cold/Warm? Moist/Dry? Why?
What do you think Air Mass #2 would be like in April? Why?

4. Air Masses - Origins Maritime tropical (mT) Continental tropical (cT)
warm and humid
Continental tropical (cT)
warm and dry
Maritime polar (mP)
cold and humid
Continental polar (cP)
cold and dry
Arctic (A)
even colder!

6. Air masses don’t just affect the US!!

7. Worksheet – Transparency 18
Answer questions on the back

8. Weather Fronts
Form where two air masses with different characteristics collide
Four types
Cold
Warm
Occluded
Stationary

9. Cold Front Cold air moves in on existing warm air (blue triangles)
Rapidly rising warm air  cools, condenses
Thunderstorms common

10. Cold Front

13. Warm Front Warm air invades area of cool air (red circles)
Warm air rises over cool air  cools, condenses
Rain common

14. Warm Front

16. Cold Front vs. Warm Front
View Animation

17. Occluded Front
Warm air gets trapped between two cold fronts (red circles and blue triangles/purple circles and triangles)
Warm air forced up  cools, condenses
Complex weather, rain/snow, thunderstorms

18. Occluded Front

19. Stationary Front No mixing (blue triangles and red circles)
Air masses push against each other, but neither moves
Parallel winds
Hard to predict weather

20. Weather fronts from Monday

21. Worksheet – Transparency 19
Fill out the questions on the back. Color the front if it helps you.