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Wind speed on the Beaufort scale is based on the empirical relationship: [6] v = 0.836 B 3/2 m/s; v = 1.625 B 3/2 knots (=) where v is the equivalent wind speed at 10 metres above the sea surface and B is Beaufort scale number.
Due to a tailwind helping to enhance the speed of the athlete in events like certain sprint races (100 and 200 metres), 100/110 metres hurdles, the triple jump and the long jump, there is a limit to how much wind assistance the athlete may compete under if the performance is to establish a record.
Meteorological data includes wind speeds which may be expressed as statute miles per hour, knots, or meters per second. Here are the conversion factors for those various expressions of wind speed: 1 m/s = 2.237 statute mile/h = 1.944 knots 1 knot = 1.151 statute mile/h = 0.514 m/s 1 statute mile/h = 0.869 knots = 0.447 m/s. Note:
An anemometer is commonly used to measure wind speed. Global distribution of wind speed at 10m above ground averaged over the years 1981–2010 from the CHELSA-BIOCLIM+ data set [1] In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in ...
The power law is often used in wind power assessments [4] [5] where wind speeds at the height of a turbine ( 50 metres) must be estimated from near surface wind observations (~10 metres), or where wind speed data at various heights must be adjusted to a standard height [6] prior to use.
The equation to estimate the mean wind speed at height (meters) above the ground is: = [ + (,,)] where is the friction velocity (m s −1), is the Von Kármán constant (~0.41), is the zero plane displacement (in metres), is the surface roughness (in meters), and is a stability term where is the Obukhov length from Monin-Obukhov similarity theory.
According to one source, [39] the wind gradient is not significant for sailboats when the wind is over 6 knots (because a wind speed of 10 knots at the surface corresponds to 15 knots at 300 meters, so the change in speed is negligible over the height of a sailboat's mast). According to the same source, the wind increases steadily with height ...
Roughness length is a parameter used in modeling the horizontal mean wind speed near the ground. In wind vertical profile such the log wind profile, the roughness length (with dimension of length and SI unit of metres) is equivalent to the height at which the wind speed theoretically becomes zero in the absence of wind-slowing obstacles and ...