Anemometer

An instrument used to measure the velocity of moving air. A cup-type anemometer uses a series of hemispherical metal cups mounted on arms on a shaft. The air blows the cups and rotates the shaft. A counter measures the number of revolutions the shaft makes in a given period of time and converts this into wind speed. A fan-type anemometer uses a small, multibladed propeller, turned by the air moving through it. The faster the air flows, the faster the fan turns. The dial on the anemometer may be marked in feet per second, meters per second, kilometers per hour, miles per hour, or knots.