Wind speed 1. The strength or speed of the wind can also be measured. 2. The instrument used to measure wind speed is an anemometer.
An anemometer consists of three cups attached to horizontal arms. The arms are attached to a vertical rod. As the wind blows, the cups rotate, making the rod spin. The stronger the wind blows, the faster the rod spins. The anemometer counts the number of rotations, or turns, and this is used to calculate wind speed.
3. Wind speed is measured in kilometres per hour (kph). It is usually averaged over a short period of time because the wind speeds are not consistent, meaning they do not always blow with the same intensity.
Wind strength can also be measured using the Beaufort scale. It is based on an observation of how much damage the wind causes rather than measurement. Wind strength categories range from 1 for calm to 12 for a hurricane-force wind.
: Figure 13.32 An anemometer
4. When the isobars are closer together on a weather map, the wind will be stronger. When they are further apart, the wind will be lighter.
