19 terms

Air Masses And Fronts Study Guide

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Air masses
A huge body of air that has similar temperature, Humidity and air pressure at any given height.
Tropical
Warm air masses form in the tropics and have low air pressure.
Polar
Cold air masses form north of 50 degrees north latitude and south 50 degrees south latitude.
Maritime
Air masses form over Oceans, so the air becomes very humid.
Continental
Air masses form over land and are drier than maritime air masses.
Maritime Tropical
Warm humid air masses that form over tropical oceans. In the summer they usually bring hot, humid weather. In the winter, a humid air mass can bring heavy rain or snow.
Maritime Polar
Cold humid air masses form over the icy cold North Pacific and North Atlantic oceans. Even in the summer, these masses of cool, humid air can often bring fog, rain and cool temperatures to the West Coast.
Continental Tropical
Hot, dry air masses form mostly in the South and bring hot, dry air to the southern plains.
Continental Polar
Large continental polar air masses form over central and Canada and bring cold weather with very little humidity.
Prevailing Westerlies
The major wind belts over the continental U.S. push air from west to east.
Jet Streams
Bands of high-speed winds about 10 km above Earth's surface.
Fronts
The boundary where two air masses meet, but do not mix. Storms and changeable weather often develop along front.
Cold Front
A fast moving cold air mass overtakes a swarm air mass. When a rapidly moving cold air mass runs into a slow moving warm air mass, the denser cold air slides under the less dense warm air causing it to rise. This results in abrupt weather changes including thunderstorms.
Warm Front
Warm air mass overtakes a slower moving cold air mass. Because the cold air is more dense than warm air, the warm air moves over the cold air. After a warm front passes through an area, the weather is likely to be warm humid.
Stationary Front
Cold and warm air meet and neither can move the other. the two air masses face each other in a "standoff." It may bring days of clouds and precipitation.
Occluded Front
A warm air mass is caught between two cooler air masses. The weather may turn cloudy and rain or snow may fall.
Isobars
lines that connect places on the map that have the same air pressure.
Cyclone
A swirling center of low pressure. (less dense) The winds spin inward and counterclockwise in the Northern Hemisphere. As air rises in a cyclone, the air cool forming clouds and precipitation. Cyclones and decreasing air pressure bring clouds, winds precipitation.
Anticyclone
High pressure centers of dry air. (more dense) Air spins outward from the center of an anticyclone moving toward areas of lower pressure. air falls in an anticyclone and generally brings dry, clear weather.