Air Masses and Fronts

In the United States , air masses generally move from west to east.

Cold air moves in under a warm air mass, often bringing winds and thunderstorms in a cold front.

After a cold front passes, the weather is usually cooler and drier.

Warm air moves up and over a cold air mass in a warm front.

After the warm front, the weather is usually warmer and drier.

When a cold front and warm front meet an occluded front is formed.

When air masses meet and stop moving over an area, they produce a stationary front.

Air Masses and Fronts

A front is a boundary between air masses with different temperatures. It marks the leading edge (front) of the air mass.

Fronts often cause rainy, unsettled weather. An air mass is large region of air that has

similar properties (humidity and temperature).

Air masses:Continental Polar – dry, cold airContinental Tropical – dry, hot airMaritime Polar – moist, cool airMaritime Tropical – moist, warm air