Leonardo da Vinci is often credited with designing an anemometer, an instrument for measuring wind speed.
His design used a light, movable plate whose movement could indicate the force of the wind. Leonardo included the instrument among his studies of air, flight, and atmospheric motion. Measuring wind was important to his investigations of flying machines because wind affects lift, drag, and the behavior of wings.
The word anemometer comes from the Greek name Aeolus, associated with the winds. Modern anemometers commonly use cups, propellers, or ultrasonic sensors, so Leonardo's plate design differs substantially from instruments used at weather stations today.
Leonardo's device should not be confused with a barometer, which measures air pressure, or a wind vane, which indicates direction. An anemometer's defining purpose is measuring wind speed or force.