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WEATHER
Lesson 3 - Page 5

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Thickening cumulus clouds warn of the coming cold front. Cold polar air cuts in sharply beneath the warm, moist tropical air. The cold air mass goes under the warm air mass at a steep angle. Strong winds between the lower and upper air masses can cause violent storms. Huge cumulonimbus many build up all along the front, bring heavy rains and sometimes thunderstorms as it passes over.

A warm front is when warm, moist air from the tropics, slides over a wedge of cold polar air. As the warm air moves over the cold air, wispy cirrus clouds form and a milky veil of cirrostratus clouds can be seen. Above the base of the front, clouds thicken first with altostratus above great, gray nimbostratus clouds. A rain storm falls in the cold sector beneath the front.

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Cold front

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Warm front

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