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
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