Aviation Glossary - Cold Front

Cold Front

Any non-occluded front which moves in such a way that colder air replaces warmer air.

source: FAA Aviation Weather for Pilots (AC 00-6A)

In weather, the leading edge of a cold air mass displacing a warmer air mass.

source: FAA Balloon Flying Handbook (FAA-H-8083-11)

Any nonoccluded front that moves in such a way that colder air replaces warmer air.

source: FAA Parachute Rigger Handbook (FAA-H-8084-17)

Any nonoccluded front that moves in such a way that colder air replaces warmer air.

source: FAA Pilot Guide: Flight in Icing Conditions (AC 91-74A)

The boundary between two air masses where cold air is replacing warm air.

source: FAA Weight Shift Control Handbook (FAA-H-8083-5)

A zone separating two air masses, of which the cooler, denser mass is advancing and replacing the warmer.

source: NOAA National Weather Service Glossary

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 30 °C (54 °F). 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.

The cooler and denser air wedges under the less-dense warmer air, lifting it. This upward motion causes lowered pressure along the cold front and can cause the formation of a narrow line of showers and thunderstorms when enough moisture is present. On weather maps, the surface position of the cold front is marked with the symbol of a blue line of triangles/spikes (pips) pointing in the direction of travel. A cold front's location is at the leading edge of the temperature drop off, which in an isotherm analysis would show up as the leading edge of the isotherm gradient, and it normally lies within a sharp surface trough. Cold fronts move faster than warm fronts and can produce sharper changes in weather. Since cold air is denser than warm air, it rapidly replaces the warm air preceding the boundary.

In the northern hemisphere, a cold front usually causes a shift of wind from southwest to northwest clockwise, also known as veering, and in the southern hemisphere a shift from northwest to southwest, in an anticlockwise manner. Normally, cold fronts can be marked by these characteristics:

source: Wikitionary / Wikipedia and Related Sources (Edited)