| Meteorology. the variable frontal zone of middle latitudes separating air masses of polar and tropical origin. |
| polar front n. The region or boundary separating air masses of polar origin from those of tropical or subtropical origin. |
| polar front
The region or boundary separating air masses of polar origin from those of tropical or subtropical origin. The position of the polar front during winter in a particular hemisphere is at approximately 30° latitude, while in the summer it is at approximately 60° latitude. The convergence of warm and cool air masses along the polar front often produces cyclonic wind systems. |