6. Surface wind

Wind is a three-dimensional vector quantity, but for everyday meteorological purposes, we are only interested in its projection onto a horizontal plane. At a given point, the wind vector is the sum of a relatively stable vector representing the average air flow (average wind) and a vector subject to rapid random variations (gusts).

In meteorology, for synoptic purposes, wind speed and direction are averages calculated over a period of ten minutes. These averages are generally supplemented by measurements of maximum wind gusts. For local aeronautical reports, two-minute averages are used. Wind direction is expressed relative to true north.

The maximum wind speed, or maximum gust, is measured over a specific period of time, typically 10 minutes, 1 hour, several hours, or 24 hours, depending on usage. The time at which this gust was measured...