Wind gust World Meteorological Organization. Any significant variation at this mean wind during the ten minutes preceding the observation are noted as gusts in messages such as METAR. It is generally reported in METAR when the peak wind speed reaches at least 16 knots and the variation in wind speed between the peaks and average wind is at least 9 to 10 knots. In marine meteorology, the top speed of a burst is expressed in meters per second (m/s) or in knots, while the Beaufort scale is used for reporting the mean speed. When the maximum speed exceeds the average speed by
Wind-powered vehicle sail. Both land yachts and ice boats have low forward resistance to speed and high lateral resistance to sideways motion. Aerodynamic forces on sails depend on wind speed and direction and the speed and direction of the craft ( "V" ). The direction that the craft is traveling with respect to the "true wind" (the wind direction and speed over the surface – "V" ) is called the "point of sail". The speed of the craft at a given point of sail contributes to the "apparent wind" ( "V" )—the wind speed and direction as measured on the moving craft.