Search results
Results from the WOW.Com Content Network
In Canada, reference wind pressures are used in design and are based on the "mean hourly" wind speed having a probability of being exceeded per year of 1 in 50. The reference wind pressure q is calculated using the equation q = ρv 2 / 2 , where ρ is the air density and v is the wind speed.
Using this formula the highest winds in hurricanes would be 23 in the scale. F1 tornadoes on the Fujita scale and T2 TORRO scale also begin roughly at the end of level 12 of the Beaufort scale, but are independent scales, although the TORRO scale wind values are based on the 3/2 power law relating wind velocity to Beaufort force. [7]
Knowing the wind sampling average is important, as the value of a one-minute sustained wind is typically 14% greater than a ten-minute sustained wind. [16] A short burst of high speed wind is termed a wind gust ; one technical definition of a wind gust is: the maxima that exceed the lowest wind speed measured during a ten-minute time interval ...
The time that a sonic pulse takes to travel from one transducer to its pair is inversely proportionate to the speed of sound in air plus the wind velocity in the same direction: = (+) where is the time of flight, is the distance between transducers, is the speed of sound in air and is the wind velocity. In other words, the faster the wind is ...
The apparent wind is the wind experienced by an observer in motion and is the relative velocity of the wind in relation to the observer. [citation needed]The velocity of the apparent wind is the vector sum of the velocity of the headwind (which is the velocity a moving object would experience in still air) plus the velocity of the true wind.
In common usage, wind gradient, more specifically wind speed gradient [1] or wind velocity gradient, [2] or alternatively shear wind, [3] is the vertical component of the gradient of the mean horizontal wind speed in the lower atmosphere. [4] It is the rate of increase of wind strength with unit increase in height above ground level.
For vector fields (such as wind velocity), the zonal component (or x-coordinate) is denoted as u, while the meridional component (or y-coordinate) is denoted as v. In plasma physics, "zonal flow" means poloidal, which is the opposite from the meaning in planetary atmospheres and weather/climate studies.
The log wind profile is generally considered to be a more reliable estimator of mean wind speed than the wind profile power law in the lowest 10–20 m of the planetary boundary layer. Between 20 m and 100 m both methods can produce reasonable predictions of mean wind speed in neutral atmospheric conditions.