Anemometer

An anemometer is instrument used to measure the velocity (speed) of the wind.

Most anemometers are made with four "cups" mounted on arms to a low-friction hub... a bit like a micro savinous wind turbine. They are not sensitive to the direction of the wind which makes them simpler mechanically and provides a more linear output than a "propeller" type turbine. This also means that an anemometer is not, by itself, capable of sensing wind direction.