Leonardo da Vinci improved an anemometer for recording wind direction and strength.
An anemometer is an instrument used to measure wind speed, while related designs can also indicate wind direction. Leonardo's version used a plate or surface that moved with the wind and a graduated scale to show how strongly the wind was blowing. He studied the instrument in connection with flight and atmospheric movement.
The word comes from the Greek name Aeolus, the keeper of the winds in mythology. Leonardo's work did not create every later form of anemometer, but it helped develop the idea of turning wind pressure into a readable measurement. Modern instruments commonly use rotating cups, propellers, or ultrasonic sensors.
An anemometer should not be confused with a barometer, which measures air pressure, or a hygrometer, which measures humidity. Leonardo's instrument is important because it connects his practical machine studies with systematic observation of the atmosphere.