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 power the volume of air passing through "A" (which is considered perpendicular to the direction of the wind); "Avtρ" is therefore the mass "m" passing through "A". Note that ½ "ρv" is the kinetic energy of the moving air per unit volume. Power is energy per unit time, so the wind power incident on "A" (e.g. equal to the rotor area of a wind turbine) is: Wind power in an open air stream is thus "proportional" to the "third power" of the wind speed; the available power increases eightfold when the wind speed doubles. Wind turbines for grid electric power therefore