Anemometers - Wind speed
The anemometers They are essential instruments in meteorology and climatology for measuring the speed and, in some cases, the direction of the wind. There are various types of anemometers, each with specific operating principles and particular applications. The main types are detailed below:
1. Cup Anemometers: They consist of three or four cups mounted at the ends of horizontal arms that rotate around a vertical axis. When the wind blows, the cups move, and the speed of rotation is proportional to the wind speed.
2. Hot Wind Anemometers: They measure wind speed by varying the temperature of an electrically heated wire. Wind speed affects the cooling rate of the wire, allowing wind speed to be calculated.
3. Wind Chill Anemometers: They use a wind-cooled wire. The wind speed is determined by measuring the amount of electric current needed to keep the wire at a constant temperature.
4. Taut Wire Wind Anemometers: They consist of a taut wire that vibrates at a frequency that depends on the wind speed. By measuring the vibration frequency, the wind speed can be determined.
5. Electrical Resistance Wind Anemometers: They measure wind speed by measuring the electrical resistance of a wind-sensitive material. Wind speed is calculated from the variation in resistance.
6. Ultrasonic Wind Anemometers: They measure wind speed by measuring the time taken for an ultrasonic wave to travel between two transducers. Wind speed affects this transit time, allowing wind speed to be calculated.
7. Wind Pressure Anemometers: They measure wind speed by varying the static and dynamic pressure in a Pitot tube. The pressure difference is used to calculate wind speed.
8. Impact Wind Anemometers: They measure wind speed by the force exerted by the wind on a flat surface perpendicular to its direction. The impact force is used to calculate wind speed.
9. Rotational Wind Anemometers: They measure wind speed by rotating a horizontal axis exposed to the wind. The speed of rotation is proportional to the wind speed.
10. Buoyancy Wind Anemometers: They measure wind speed by the force exerted by the wind on a hollow sphere or blade. The equilibrium position of the sphere or blade is used to calculate the wind speed.
The choice of anemometer type depends on factors such as the required accuracy, the installation environment and the specific purpose of the measurement. These devices are essential for natural resource management, weather forecasting and protection against adverse weather events.
