6. AIR MASSES
Air mass- a large body of air that has the same properties as the surface over which it develops.
Global air masses

7. AIR MASSES DON’T WRITE…Just Look
Air masses are classified according to their source regions. (where they came from).
COLD air masses = Polar Areas “P”
WARM air masses = Tropical Areas “T”
Ocean = Maritime “m”
Land = Continental “c”

8. AIR MASSES This means REALLY cold Four main types of Air Masses
Continental Polar (cP)
Maritime Tropical (mT)
Continental Tropical (cT)
Maritime Polar (mP)
Continental Arctic (cA)
This means REALLY cold

9. AIR MASSES Cold, dry air from the north. (cP)
There are 7 major air masses that affect weather in the United States.
Cold, dry air from the north. (cP)
Warm, moist air from the southeast. (mT)
Warm, moist air from the Gulf of Mexico (mT)
Warm moist air from the southwest. (mT)
Hot, dry air from the south. (cT)
Cool, moist air from the northwest. (mP)
Cool, moist air from the northeast. (mP)
Frigid, dry, cold air from artic regions(cA)

12. Air Masses of the World

13. FRONTS

14. FRONTS
Front- the boundary between two different air masses. Storms and precipitation occur along these fronts.
Warm front
Warm air is pushed over a mass of cold air.
Nimbostratus clouds form that can produce continuous rain.

15. Warm Front

17. FRONTS Cold fronts Cold air is shoved underneath a warm air mass.
Cumulonimbus clouds form that can produce showers, lightning, hail, tornadoes and high winds.

18. Cold Front

20. FRONTS
Squall Line
A line of heavy thunderstorms that form just ahead of a fast moving Cold Front.

21. Squall Line

22. FRONTS Stationary front
A warm or cold front that stays in the same place for an extended period of time.
Weather is similar to that produced by a Warm Front.

23. FRONTS
Occluded front
Occurs when two cool air masses merge and force warm air between them to rise.
Strong winds and heavy precipitation may occur.

24. PRESSURE SYSTEMS
High pressure systems- are areas of descending air. This makes it very difficult for clouds to form and is typically associated with nice weather.
Low pressure systems- are areas of ascending air. This creates the correct environment for clouds to form.