A cold front is a warm-cold air boundary with the colder air replacing the warmer. As a cold front moves into an area, the heavier cool air pushes under the lighter warm air that it is replacing. The warm air becomes cooler as it rises and, if the rising air is humid enough, the water vapor it contains will condense into clouds and precipitation may fall.
As a cold front moves into an area, the heavier cool air __________ the lighter warm air that it is replacing.
pushes under |
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cancels out |
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mixes with |
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pushes above |