Definition

A cold flow of air travelling down an orographic slope (eg. hill or mountain).

Description

During and after sunset, particularly on a clear day/night, air at and near the top of elevated land surfaces, particularly over snow-covered surfaces, cools relatively quicker than air at lower altitudes. As air cools it becomes denser and therefore heavier. The cold air then flows down the side of the mountain, resulting in a katabatic flow (or wind). Fig. 1 is a simple diagram denoting the above text. The flow may be as strong as 100 knots, and generally more pronounced in intensity to its opposite, anabatic wind.