* Anemometer History *
There are quite a few different types of anemometer, all of which measure wind pressure and velocity. In 1846, John Thomas Romnay Robertson invented a simple design known as a cup anemometer. Four horizontal arms hold the hemispherical shaped cups, these are at right angles to each other, and mounted on a vertical shaft. The number of turns that the cups made over a certain time period could predict the speed of the wind. Although this was a clever desing, it proved to have flaws. The inventor first thought that the length of the arms, and size of the cups didn’t make a difference to the overall wind speed prediction, but it was later proved that the size of the components used did give a different wind speed reading. As a result a more efficient three cup anemometer was invented by, John Patterson in 1926.
* Windmill Anemometer and it’s Uses *
Windmill anemometers also measure wind speed, but unlike the cup anemometer, the windmill is mounted horizontally. There are also devices known as the laser doppler anemometer, which uses a beam of light to gather wind speed. Particles and air molecules float around where the beam is, light is reflected back to the device, this is then measured in accordance with the original light beam. A doppler shift is created as the particles move faster, then the wind speed through the laser can be measured.
* Uses of a Hot Wire Anemometer *
Hot wire anemometers are more commonly used for high frequency response measurements. Fine wire is used, and heated to an above ambient temperature. Air that flows past the wire will cool the wire down, the effects of this cooling process can be recorded in order to determine the resistance of the wire and the flow velocity. There are also sonic anemometers that measure wind direction and speed. They do this by way of ultrasonic sound waves. Automated weather stations prefer this method as the device doesn’t move around a lot. These are also used in conjunction with ship navigation, wind turbines, and small weather stations.
* Tube Anemometer Uses *
Tube anemometers were made in different forms over the years, but the one that is usually remembered was invented by, James Lind, in 1775. This was basically a u-shaped glass tube with liquid and a anemometer, one end was bent horisontally to face the wind, and the other stayed in a vertical position. When the wind blows through these tubes, the liquid changes, and the anemometer can determine air pressure.
* What Further Uses are there for an anemometer? *
As well as velocity anemometers there is also pressure anemometers. Plate anemometers are simply shaped like a plate, as the name suggests. There have been a few designs invented over the years. Later versions were round or square shaped, and kept in accordance with the wind using a wind vane. The pressure is judged by a spring attached to the plate, the force on the spring from the plate is measured by a gauge, or recording device. These anemometers have been used to determine high wind forces on bridges.