Wind speed

Wind speed is

,

where u, v, and w are zonal, meridional, and vertical components of wind velocity. Except in unusual circumstances (e.g. in cumulus updrafts), the vertical component of the velocity is much smaller than the horizontal component. In scientific literature, wind speed is given in the unit metres per second, but it is also common to see it in knots.

Other, empirical scales exist: The Beaufort scale is a common way to assess wind speed without an anemometer, and the Fujita scale allows classification of tornadoes in six categories.