Cold-air mass and warm-air mass can contact {front, air}| when air masses start to move. Polar easterlies can meet southern westerlies {polar front}. At fronts, warm air rises and cools to make clouds and precipitation.
Cold air can replace warm air {cold front}|, or cold-air masses can move into regions. Cold fronts bring rolling dark clouds and lightning, moving fast and steep, as cold air tunnels under warm air, with hard rain. Cold fronts first make cumulonimbus clouds and later make dark low clouds and small strong storms. Cold fronts can make squall lines, from which can come tornados.
Warm air masses can move into regions {warm front}|. Warm fronts first bring high clouds, because warm air goes over cold-air top, and then low clouds, moving slow and long with steady rain. Warm fronts first make cirrus clouds, then cirrostratus clouds, then altostratus clouds, and then nimbostratus clouds, with broad light rain.
5-Earth Science-Atmosphere-Wind
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Date Modified: 2022.0225