Explanation:

Cold front: Such a front is formed when a cold air mass replaces a warm air mass by advancing into it, and lifting it up, or when the pressure gradient is such that the warm air mass retreats and cold air mass advances. In such a situation, the transition zone between the two is a cold front. The weather along such a front depends on vertical structure of the uplifted air mass, but is generally associated with a narrow band of cloudiness and precipitation. The approach of a cold front is marked by increased wind activity in warm sector and the appearance of cirrus clouds, followed by lower, denser alto-cumulous and altostratus. At actual front, dark nimbus clouds cause heavy showers. A cold front passes off rapidly, but the weather along it is violent.