A ir mass - large body of air that has similar temp. and moisture

1. Air mass- large body of air that has similar temp. and moisture - move by prevailing winds and upper air currents Front - boundary between 2 different air masses.

2. Air Masses - form over large, flat areas of the Earth’s surface. - typically have a high pressure system at their center. Air sinks and spreads out from the same geographic region. H The air takes on the characteristics of the surface.

3. Arial View of Air Mass N E H

4. Typical Air Mass Types Arctic – very cold and very dry Continental polar – cold and dry Maritime polar – cool and moist Maritime tropical – warm and moist Continental tropical – hot and dry

5. Warm Front N E Colder air mass Warmer air mass Warm front moves north as warmer air pushes out colder air.

6. Usually brings cloudiness or steady rain

7. Cold Front N Cold front moves south as colder air pushes out warmer air. E Colder air mass Warmer air mass

8. Can bring snow or thunderstorms.

9. Stationary Front when the boundary between the two air mass is not moving. N E Colder air mass Warmer air mass

11. Occluded Front or