Fronts: the boundaries between air masses

A front is defined as the transition zone between two air masses of different density. Fronts extend not only in the horizontal direction, but in the vertical as well. Therefore, when referring to the frontal surface (or frontal zone), we referring to both the horizontal and vertical components of the front.

[Image: cross section of cold front (27K)]

The types of fronts discussed in this module include:

Fronts
Last Update: 07/25/97

Stationary Front
A front that is not moving.

Cold Front
Leading edge of colder air that is replacing warmer air.

Warm Front
Leading edge of warmer air that is replacing cooler air.

Occluded Front
When a cold front catches up to a warm front.

Dry Line
Separates a moist air mass from a dry air mass.

Air Masses

Terms for using data resources. CD-ROM available.
Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.

stationary front