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.

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

N E H Arial View of Air Mass

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

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

Usually brings cloudiness or steady rain

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

Can bring snow or thunderstorms.

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

Occluded Front or