A cup anemometer is a device used to measure wind speed. It consists of three or four cups attached to horizontal arms, which are mounted on a vertical shaft. As the wind blows, it causes the cups to rotate, and the speed of this rotation is directly related to the wind speed. These instruments are commonly used in meteorology, weather stations, and wind energy applications. They provide accurate and reliable measurements, making them essential for understanding wind patterns and assessing potential sites for wind turbines.