A cold or warm front is defined by change in temperatures and wind direction. Cold fronts are usually on the back side of a low pressure system, generally extending to the west or south from the center of the low, as the back side of the system is usually pulling cold air in from the north. On weather maps they are defined as blue triangles that point in the direction that the front is moving.
Because cold air is more dense and heavier than warm air, as
the cold air moves through it pushes the warm air up – frontal lifting along
the frontal boundary. This process
allows for clouds and precipitation to develop along and just behind the