Wind speed is measured using an instrument called an anemometer, which can record wind speed, direction, and the strength of gusts. The most common type of anemometer consists of three or four cups mounted symmetrically about a vertical spindle. The wind blowing into the cups causes the spindle to rotate, and the rate of rotation is proportional to the speed of the wind. The faster the anemometer is spinning, the stronger the wind. Wind direction is measured relative to true north and is reported from where the wind is blowing.

In addition to cup anemometers, there are other types of anemometers that can be used to measure wind speed. For example, a heated sonic anemometer can be used in extreme weather conditions, such as on the top of mountains, as it has no moving parts. The instrument measures the speed of acoustic signals transmitted between two transducers located at the end of thin arms.

Wind speed is typically measured in meters per second (m/s), miles per hour (mph), or kilometers per hour (km/h) . The normal unit of wind speed is the knot, which is equivalent to one nautical mile per hour.

In summary, an anemometer is used to measure wind speed, and the most common type of anemometer consists of three or four cups mounted symmetrically about a vertical spindle. The faster the anemometer is spinning, the stronger the wind. Wind direction is measured relative to true north, and wind speed is typically measured in meters per second, miles per hour, or kilometers per hour.