Air in motion relative to the surface of the earth. Since vertical components of atmospheric motion are relatively small, especially near the surface of the earth, meteorologists use the term to denote almost exclusively the horizontal component. Vertical winds are usually identified as such. Surface winds are measured by anemometer and wind vane; winds aloft by such systems as pilot balloon, radiosonde, or aircraft navigational techniques. See Also circulation, general circulation, turbulence, geostrophic wind, gradient wind, local winds, Beaufort wind scale, draft, cyclone, whirlwind, squall, storm.