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
Variable speed wind turbine Variable speed wind turbine Original models of wind turbines were fixed speed turbines; that is, the rotor speed was a constant for all wind speeds. The tip-speed ratio for a wind turbine is given by the following formula: formula_1 where formula_2 is the rotor speed (in radians per second), formula_3 is the length of a blade, and formula_4 is the wind speed. That is to say, for a fixed-speed wind turbine, the value of the tip-speed ratio is only changed by wind speed variations. In reference to a formula_5-formula_6 graph, which illustrates the relationship between Tip-speed ratio and efficiency, it