Front

A front is a boundary or transition zone between two air masses of different density, and thus (usually) of different temperature. A moving front is named according to the advancing air mass, e.g., cold front if colder air is advancing.[1]

In military usage, the term is also used in wartime refer to the geographic area where the bulk of fighting takes place (as opposed to a rear area).

## References[edit]

1. ↑ http://www.weather.gov/glossary/index.php?letter=f