Almost everyone has heard of the anemometer. The device is actively used in meteorological stations and is indispensable for measuring the velocity of gases in various industrial systems, such as ventilation systems.
But if the essence of his “relative” – a weather vane – is known too many, the principle of operation and purpose of the anemometer sometimes raises many questions. What kind of device is it? What does it measure and how does it function? Let’s try to understand.
What does the word “anemometer” mean?
Anemometer has another name “wind meter” and comes from two Greek words – ἄνεμος (wind) and μετρέω (to measure). In simple terms, it is an instrument that measures the wind. The Italian mathematician Leon Battista Alberti is considered the creator of the anemometer.
The device, invented by him around 1540, has since then almost unchanged. Over the following centuries, many scientists, including Robert Hooke, tried to develop their own versions of the device, with some of them falsely credited with inventing it.
In 1846, the Irish astronomer John Robinson improved the design of the anemometer with four hemispherical cups and mechanical wheels. Some new functions of the device were gained at the end of the twentieth century. Derek Weston made it possible to determine wind direction, and Dr. Andrews Flitz developed the sonic anemometer.
What is an anemometer?
In its modern meaning, an anemometer is a device that allows the measurement of wind speed or gas movement. Its scope of application covers any place where there is a need to determine the rate of movement of air currents. Besides meteorological stations, the device is used at airfields, helipads, flying clubs, and organizations that provide the opportunity to fly hang gliders.
The anemometer is not out of place at lifeguard towers and sailing vessels for which strong winds of 7 points already represent a great danger.
What does the anemometer measure?
As mentioned above, an anemometer measures the speed of air flows, but depending on the model, the devices can perform several other functions – to determine the wind direction, to calculate the atmospheric pressure, temperature, volume flow, and humidity.
In fact, such a device becomes a portable meteorological station, easy to use and transport. During measurements, it reads the information, performs analysis and displays the values got.
What anemometers are there?
Depending on the design and operating principle, anemometers are divided into mechanical and electronic. The first includes a cup and vain devices. The cup anemometer is the most common and is a rotor with hemispherical cups symmetrically placed on it.
Under the action of the wind, the rotor rotates on a vertical axis, and a mechanical counter records the number of revolutions of the cups over a certain period. The vain anemometer has a miniature wind wheel, the rotation of which is transmitted to the arrow of the mechanical counter. It is used primarily in piping and ventilation systems to calculate airflow.
Thermal anemometer refers to electronic devices and operates through an electronic circuit, which includes a wire thermosensor. The essence of the device’s functioning is to heat the filament and then measure its resistance depending on the ambient temperature.
More advanced is another electronic device – an ultrasonic anemometer. It measures the speed of air flows by measuring the speed of sounds that change according to the direction of the wind. Some models combine the functions of a manometer and a hygrometer.