Air Masses and Fronts

The term front was suggested by the Bjerkneses because the collisions of two air masses reminded them of a battlefront during a military operation. That collision often results in war-like weather phenomena between the two air masses.

Fronts develop when two air masses with different temperatures and, usually, different moisture content come into contact with each other. When that happens, the two bodies of air act almost as if they are made of two different materials, such as oil and water. Imagine what happens, for example, when oil is dribbled into a glass of water. The oil seems to push the water out of its way and, in return, the water pushes back on the oil. A similar shoving match takes place between warm and cold air masses along a front. The exact nature of that shoving match depends on the relative temperature and moisture content of the two air masses and the relative movement of the two masses.