An anemometer is a device used to measure wind speed. It typically consists of three or four cups mounted on arms that rotate around a vertical axis. As the wind blows, the cups catch the wind and cause the arms to rotate. The speed of rotation is then measured and converted into a wind speed reading.

Anemometers are used in a variety of applications, including weather stations, windmills, and aircraft. They are also used by meteorologists to study wind patterns and by engineers to design buildings and other structures that can withstand high winds.

There are two main types of anemometers: cup anemometers and sonic anemometers. Cup anemometers are the most common type and work by measuring the speed of rotation of the cups. Sonic anemometers use sound waves to measure wind speed and are more accurate than cup anemometers but also more expensive.