Wind measurement

(meteorology) The determination of three parameters: the size of an air sample, its speed, and its direction of motion.

The determination of three parameters: the size of an air sample, its speed, and its direction of motion. Air movement or wind is a vector that is specified by speed and direction; meteorological convention indicates wind direction is the direction from which the wind blows (for example, a southeast wind blows toward the northwest). Anemometers measure wind speed, while wind vanes indicate direction. On average, the wind blows horizontally over flat terrain; however, gusts, thermals, cloud outflows, and many other conditions have associated with them significant short-term vertical wind components. While research wind instruments typically measure both horizontal and vertical air movement, operational and personal wind sensors measure only the horizontal component. See also Anemometer.

There are many types of wind measurement instruments. In situ devices measure characteristics of air in contact with the instrument; often they are referred to as immersion sensors because they are immersed in the fluid (air) they measure. Remote wind sensors make measurements without physical contact with the portion of the atmosphere measured. Active remote sensors emit electromagnetic (for example, light or radio waves) or sound waves into the atmosphere and measure the amount and nature of the electromagnetic or acoustic power returned from the atmosphere. See also Lidar; Meteorological instrumentation; Meteorological radar; Wind.