meteorolthe boundary between a warm air mass and the cold air above which it is rising, at a less steep angle than at the cold frontCompare cold front, occluded front
The forward edge of an advancing mass of warm air that rises over and replaces a retreating mass of cooler air. As it rises, the warm air cools and the water vapor in it condenses, usually forming steady rain, sleet, or snow. On a weather map, a warm front is depicted as a red line with half circles whose curved sides point in the direction in which the warm air is moving. Compare cold frontoccluded front. See illustration at front.
