anemometre

An anemometer is an instrument for measuring wind speed. It is a common tool in meteorology, aviation, and environmental monitoring, and appears on weather stations, ships, aircraft, and research platforms. The term derives from Greek words for wind and measure; the French spelling is anémomètre.

There are several principal types. Mechanical cup anemometers use three or four cups on a horizontal arm mounted on a vertical shaft; wind drives rotation, and the rotation rate is related to wind speed by calibration. Propeller or vane anemometers employ a wind-driven propeller or turbine connected to a sensor, often with a wind vane to keep the device oriented into the wind; speed is inferred from rotation rate or output signals. Thermal (hot-wire or hot-film) anemometers measure wind by the cooling effect of air on a heated element; a control circuit maintains a fixed temperature or resistance, and the power required relates to wind speed. Ultrasonic anemometers determine wind velocity from the travel times of sound between transducers placed in multiple directions; they have no moving parts and can provide three-dimensional measurements. Other approaches exist mainly in research, such as laser Doppler velocimetry.

Applications and use include weather forecasting, aviation safety, wind-energy assessments, and indoor air quality monitoring.

Units, calibration, and maintenance: results are typically given in meters per second, kilometers per hour, miles per hour, or knots; devices are calibrated against standards and may require temperature compensation and periodic maintenance. Placement and exposure conditions affect readings, so standardized installation practices are used to ensure representative measurements.