Which instrument measures wind speed?

An anemometer measures wind speed.

The most familiar design has three or four cups mounted on horizontal arms. Wind pushes the cups around a central spindle, and the rotation rate is converted into wind speed. Other designs include propeller anemometers, sonic anemometers, and hot-wire instruments.

Leon Battista Alberti described an early mechanical anemometer in 1450. Modern weather stations often combine wind-speed measurements with a wind vane, which shows direction. Beaufort force is a separate descriptive scale: it estimates wind force from observed effects, whereas an anemometer provides an instrumental speed measurement.