1. Air Masses & Fronts

2. Air Mass
Air Mass: a huge body of air that has similar temperature, humidity, and pressure
Can be spread out over millions of km2 and up to 10 km deep

3. Types of Air Masses Descriptors: Types of Air Masses: Tropical = warm
Polar = cold
Arctic = very cold
Continental = dry
Maritime = wet
Types of Air Masses:
Maritime Tropical: warm & wet
Continental Tropical: warm & dry
Maritime Polar: cold & wet
Continental Polar: cold & dry
Continental Arctic: very cold & dry

4. How Air Masses Move
Westerlies – major wind belt over the US, generally pushes air masses from west to east
Jet Streams: bands of high-speed winds about 10 km above Earth’s surface, also blow west to east
Front: the boundary between air masses
When air masses collide, they do not easily mix

5. Types of Fronts
Cold Front: fast moving cold air mass collides with slower moving warm air mass
Cold fronts tend to move quickly

6. Types of Fronts
Warm Front: faster moving warm air mass collides with slower moving cold air mass
Warm fronts tend to move slowly

7. Types of Fronts
Stationary Front: when two air masses collide and don’t move for many days

8. Types of Fronts
Occluded Front: a warm air mass is trapped between two colder air masses

9. Highs & Lows
Cyclone: a spiral of warm, rising air, creating an area of Low air pressure (L)
Spins counter-clockwise
Anticyclone: a spiral of cold, falling air, creating an area of High air pressure (H)
Spins clockwise