Leonardo da Vinci developed an anemometer to record wind speed.
His design used a flat plate that moved upward or downward as wind pushed against it. A graduated scale beside the plate allowed an observer to estimate the wind’s strength. The instrument was intended to support studies of flight and air movement.
Leonardo’s anemometer was not the cup anemometer commonly seen at modern weather stations. Cup and propeller designs became standard much later because they provide more convenient continuous rotation and calibration.
The instrument is associated with Leonardo’s investigations of birds, air resistance, and flying machines. It measured the effect of wind on a surface rather than directly measuring atmospheric pressure or humidity. Those functions belong to different instruments: a barometer measures pressure, while a hygrometer measures moisture.