In
meteorology, a front is the boundary between two
air masses, usually of differing
temperatures. Fronts are charactarized by
low pressure,
clouds, and often
precipitation, although some fronts are marked by nothing but a
wind shift. Many fronts are given energy, and motion, by the
jet stream.
There are several types of fronts. When warm air is displacing cold air, the front is a warm front. A cold front is when cold air is displacing warm air. Cold fronts usually follow a day or two behind warm fronts. When a cold front meets a warm front, it creates an occluded front, and the cold front lifts the warm air entirely off the ground. If the front is not moving at all, it is a stationary front.