Anemometer, << `an` uh MOM uh tuhr, >> is an instrument that measures wind speed. There are several types of anemometers. The most common type has three or four cone-shaped cups at the end of rods that are from 2 to 8 inches (5 to 20 centimeters) long. This unit rotates on a vertical spindle. The wind pressure is greater on the concave (inward curving) side of the cups, than on the convex (outward curving) side. Because of this, the wind makes the cups rotate regardless of wind direction. The faster the wind blows, the faster the cups rotate. The wind speed is measured by the number of revolutions the cups make in a given period of time. This information is often registered on a dial on the anemometer. However, it can also be transmitted by electrical means to display devices located some distance from the anemometer itself.
