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18 Cards in this Set
- Front
- Back
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Air Mass |
A large body of air that has similar temperature and humidity at any given height. |
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What are the four types of air masses? |
The four air mass types that influence weather in North America are: Tropical, Polar, Maritime, Continental, and these combine to form the four air masses: Tropical Maritime, Tropical Contental, Polar Maritime, and Polar Continental. |
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How are air masses affected by winds and by which? |
The prevailing westerlies and jet streams move air masses across the U.S. |
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Tropical (air masses) |
Warm air mass, forms in warm areas, tends to have low pressure. |
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Polar |
Cold air mass, forms above 50 latitude, high air pressure. |
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Maritime |
Forms over oceans, high humidity |
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Continental |
forms over land, low humidity |
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Fronts |
Boundaries of air masses, where they meet. Cause changes in weather. |
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Cold Front |
A fast moving cold air mass overtakes a warm air mass. Warm, humid air is forced up quickly, causing it to cool. Results in abrupt weather changes. Can cause thunderstorms. |
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Warm Front |
A fast moving warm air mass overtakes a cold air mass. Warm air drifts up and over the cold air mass. Causes light rain or snow. |
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Stationary Front |
Cold and warm air masses meet, but cannot move each other. Cause extended periods of rain, snow, fog, clouds as the warm air is cooled by the cool air. |
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Occluded Front |
Most complex front. Warm air mass caught between two cool air masses. Warm air is cut off (occluded) from the ground. Ground level cools and rain or snow may fall. |
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Cyclone |
(Not to be confused with Pacific Hurricanes) Low pressure area ("Lows"), warm air in the center rises, air pressure decreases, air flows toward the center, air spirals in and up in a counterclockwise manner. Warm air cools and clouds, wind, and precipitation may occur. |
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Anticyclone |
Opposite of a cyclone, high pressure area of dry air ("Highs"), Winds spiral outward in a clockwise manner, moving toward Lows. Results in dry, clear weather. |
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How do the jetstreams affect our weather? |
During the winter, they form a barrier blocking off warm air from the lower region, and during the summer they block cooler air from the upper region. |
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What are always formed during a front? |
Clouds. |
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What weather do cyclones cause? |
All weather. |
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Study all Figures (3,6,5). Which have you memorized? |
All :) |
