Download Air Masses and Weather

Earth’s Weather
Air Masses and Weather
Air Masses

Air Masses = huge bodies of air that appear like
large, slowly changing clumps that cover
thousands of kilometers.

Moisture content and temperature used to
describe air masses




Moist air masses form over water
Dry air masses form over land
Cold air masses form at the Earth’s poles
Warm air masses form at the equator
Air Masses Meet

Front = the border at which two air masses meet
because they don’t mix

Cold Front forms when a cold air mass moves in to
replace the warm air mass. When the warm air is forced
up, it cools and forms clouds, rain, and sometimes
thunderstorms

Warm Front forms when warm air moves over a mass of
cold air. As the warm air rises up over the colder air,
clouds form many miles ahead of the front and rain or
snow falls as the front passes. Then the sky clears

Stationary Front forms when a front stops moving and
can stay in place several days. Lots of rain or snow can
occur.
Air Masses Move

Weather changes as air masses move. Wind
speed often changes as a front approaches and
changes direction as a front passes.

Air pressure drops as a warm front approaches
and rises as a cold front approaches

Warm fronts bring warm temperatures; cold
fronts bring cold temperatures.