The animation below is a vertical cross section depicting the development of precipitation ahead of and along a cold front. The surging blue region represents the cold air mass behind the cold front (solid blue line) and the yellow areas indicate the warm moist air mass ahead of the front.
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As the cold air mass propagates, it lifts the warmer less dense air ahead of it (red arrows). The air cools as it rises and the moisture condenses to produce clouds and precipitation ahead of and along the cold front. In contrast to lifting along a warm front, upward motions along a cold front are typically more vigorous, producing deeper clouds and more intense bands of showers and thunderstorms. However, these bands are often quite narrow (a couple hundred kilometers across) and move rapidly just ahead of the cold front.