Wind gust 10 to 15 knots, the term "gusts" is used while "strong gusts" is used for departure of 15 to 25 knots, and "violent gusts" when it exceeds 25 knots. Wind gust A gust or wind gust is a brief increase in the speed of the wind, usually less than 20 seconds. It is of a more transient character than a squall, which last minutes, and is followed by a lull or slackening in the wind speed. Generally, winds are least gusty over large water surfaces and most gusty over rough land and near high buildings. The wind is measured using
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