gust

A transient deviation of wind intensity relative to its average value, which may or may not be accompanied by a change in direction. That deviation can be positive or negative and occurs over a brief span of time. In Meteorology only that which involves a sudden increase in speed is counted as a gust. Wind gusts can be due to mechanical or thermal factors, being particularly evident near the ground. Near the Earth's surface, the interaction of air currents with obstacles in their path, as well as the roughness of the terrain, generate turbulence, which manifests itself in the form of gusts. In the continuous record of wind measured with an anemometer, instantaneous gusts are obtained by averaging over intervals of a few seconds.