cold front

A front that forms as a consequence of a cold air mass pushing against a warm air mass, penetrating beneath it like a wedge and forcing it to rise impetuously. On weather maps it corresponds to the line of intersection of the cold frontal surface (CFS) and the Earth's surface. The aforementioned CFS is the zone of separation between a warm air mass (leading) and a cold one (trailing). Graphically, it is represented with a thick blue line with blue triangles pointing in the direction the front is advancing. The cloudiness associated with it is cumuliform, producing precipitation in the form of showers, occasionally thundery. As the cold front passes, the skies tend to clear considerably, as a consequence of the entry of the cold air mass, the wind backs/veers to a northerly component and atmospheric pressure rises sharply and markedly. In that trailing zone, post-frontal showers sometimes occur. Ahead of the cold front lies the warm front, the two separated by a zone called the warm sector. The push of the trailing cold air makes the cold front travel at a greater speed than the warm front. When it catches up to and overtakes it, an occluded front or occlusion forms.