1. Air Masses and Fronts

2. Air Mass
A large volume of air that takes on the temperature and humidity characteristics of the area over which it develops.

3. cP cT mP mT cA North American Air Masses SE Symbol Name Source Region
Characteristics
Direction of Movement cP
Continental
Polar
West / Central Canada
Cold
Dry SE cT
Tropical
SW U.S
Northern Mexico
Hot NE mP
Maritime
Northern
Atlantic / Pacific
Wet
East (pacific)
West (Atlantic) mT
Gulf of Mexico cA
Arctic
Arctic Circle
Very Cold

4. How do clouds form? Rising air cools due to decreased air pressure.
Water vapor condenses because air temperature reaches the dew point.
Clouds and precipitation form this way.

6. Fronts: Where air masses meet.
Warm Front:  Warm air meets cold air.  Less dense warm air rises over the cold air at a gentle angle. 
Produces showers and stratus clouds.

7. Cold Front
Cold air invades warm air, pushing the warm air up at a steep angle.
Produce cumulus and cumulonimbus clouds.
Showers and Thunderstorms

8. Occluded Fronts
Cold Occlusion: when the air behind the front is colder than the air ahead of the front.
Coldest air undercuts the cool air ahead of the front.
(Like a cold front)

9. Warm Occlusion
Air behind the front is warmer than the air ahead of the front. (Acts like a warm front.)
Stationary Front: Cold and Warm air are at a standoff. Can produce days of showers / storms.