Anemometers

Q: What is an anemometer?

A: An anemometer is a meteorological instrument used for measuring wind speed, says Prescott Bishop of Texas A&M University. “Although many different kinds of anemometers exist, the most traditional one used is known as a cup anemometer,” he explains. “Cup anemometers have three or four hemispherical cups attached to arms that meet at a center point on a swivel. The cups are spaced apart equally in distance and rotate at a speed proportional to the speed at which the wind is blowing. These cup anemometers, however, can only tell the speed of the wind but not its direction. By combining a propeller with a weathervane, windmill anemometers show the direction of the wind as well at its speed. Advanced anemometers such as laser Doppler and sonic anemometers are more expensive and less common.”

Q: How are anemometers useful in weather forecasting?

A: Although the wind itself is an important component of weather, knowing the speed and direction from which the wind is approaching can help indicate future patterns by looking upstream, Bishop points out. “Although anemometers can only tell the winds at the surface, they still have the ability to show which way temperatures, humidities and storms are moving as well as how soon the changes can be expected,” he notes. “Combined with weather-balloon data of winds from the upper atmosphere, the large network of anemometer data is plugged into computer forecast models and has proven to be one of the most important components in predicting the weather.”