What is "cold front"

n. (context meteorology English) A cold front is the leading edge of an advancing mass of cold air.

n. the front of an advancing mass of colder air [syn: polar front]

__NOTOC__ "Cold Front" is the eleventh episode (production #111) of the television series Star Trek: Enterprise, and was written by Stephen Beck and Tim Finch. Robert Duncan McNeill served as director for the episode.
This episode reveals more about the Temporal Cold War story arc first introduced in Broken Bow. Captain Archer is confronted by a member of his crew who claims to be from nine hundred years in the future – and is there to capture a Suliban operative who has boarded Enterprise.

A cold front is defined as the leading edge of a cooler mass of air, replacing at ground level a warmer mass of air, which lies within a fairly sharp surface trough of low pressure. It forms in the wake of an extratropical cyclone, at the leading edge of its cold air advection pattern, which is also known as the cyclone's dry conveyor belt circulation. Temperature changes across the boundary can exceed . When enough moisture is present, rain can occur along the boundary. If there is significant instability along the boundary, a narrow line of thunderstorms can form along the frontal zone. If instability is less, a broad shield of rain can move in behind the front, which increases the temperature difference across the boundary. Cold fronts are stronger in the fall and spring transition seasons and weakest during the summer. When a cold front catches up with the preceding warm front, the portion of the boundary that does so is then known as an occluded front.

Cold Front is a 1989 Canadian-American crime-thriller film directed by Allan A. Goldstein and starring Martin Sheen, Michael Ontkean and Beverly D'Angelo.