The Atmosphere

Air and Air Pressure

What is a dry front

An occluded front occurs whenever a cold front, instead of merely overtaking warm air, actually separates and breaks apart warm mass of air. Occluded fronts come in both warm and cold varieties. In a warm occluded front, the cold air at the advancing side of the warm front is cooler than the air in the cold front that is overtaking it. In a cold occluded front, the cold air at the advancing side of the warm front is warmer than the air in the advancing cold front.

A dry front—also called a dry line or dew point front—is a borderline separating a mass of dry air from one of much more humid air. Often found east of the Rocky Mountains, these fronts will find the warmer, drier air lifting the cooler, more humid air ahead of it in the higher altitudes, while humid air near the ground is denser than the dry air and the drier air will flow over it. The result is an air mass reversal that can precipitate the formation of cumulonimbus clouds, thunderstorms, and, quite often, tornadoes.



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