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Instrument for measuring the speed of airflow. The most familiar instruments for measuring wind speeds are the revolving cups that drive an electric generator (useful range approximately 5–100 knots). For very low airspeeds, a unit in which revolving vanes operate a counter measures the airspeed. For strong, steady wind speeds (in wind tunnels and aboard aircraft in flight), a pitot-tube anemometer is often used; the pressure difference between the interior of the tube and the surrounding air can be measured and converted to airspeed.
This entry comes from Encyclopædia Britannica Concise. For the full entry on anemometer, visit Britannica.com.