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Types of Anemometers

8/8/2012 2:12:06 PM | by Anonymous

Anemometers

Anemometers are meteorological devices sed to measure wind speeds and can commonly be found in weather stations. They get their name from the Greek word for wind; anemos. Not only instruments used in meteorology but also in aerodynamics instruments that take airspeed measurements are described as anemometers. The first known description of an anemometer is said to be around 1450. Measurements of wind can be taken in two different forms, the speed of the wind and the pressure. However, there is a connection between these two. Anemometers can be divided into two different classes, measuring the speed of the wind or the pressure. As there is a connection between wind speed and pressure, an anemometer measuring the speed for example would still be able to provide information on the pressure of the wind. There are several different designs of anemometers that exist in the industry today, each using different methods to measure the speed or pressure of the wind.

Types of Anemometers

Cup Anemometers

Also known as rotational anemometers, cup anemometers are the simplest types of anemometers and have been around for a very long time. The make up of these meters consists of a vertical central pole and four horizontal arms at the top that have a cup attached to each of them. As wind presses against these cups, the arms at the top rotate around the central pole. The speed of the rotation would determine the speed of the wind. The speed of the wind is usually observed through digital readouts in these anemometers. Researchers, meteorologists and many educational institutions worldwide make use of these anemometers for commercial or research activities. Not only for commercial, but one can make their own anemometer for their own personal use. For these meters, the speed of the wind can be calculated by multiplying the revolutions the cups make in a minute with the circumference that the cups create. This method would provide a rough estimate of the speed of the wind. A disadvantage of these meters is that they are prone to friction. As the cups rotate around their axis, they encounter friction which could affect the accuracy of the readings.

Windmill Anemometers

These anemometers, just like the cup anemometers, measure the velocity of the wind. They are also able to determine the direction of the wind as they have a propeller that is attached to the front of the device with a tail section behind, on the same axis as the propeller on a central pole. As wind presses against the propeller, it spins it and the faster the propeller spins, the faster is the velocity of the windmill anemometer. The windmill anemometer adopts that shape of a windmill, hence its name. The windmill anemometer has to be parallel to the direction of the wind in order for it to function properly and provide accurate results. The turning effect of the propeller causes the mechanism in the anemometer to be able to calculate the speed of the wind.

Ultrasonic

Ultrasonic, as its name would suggest, involves sonic pulses to measure the velocity of the wind. The device sends sonic pulses across a path to sensors located across which are able to sense the incoming pulses. As the movement of wind is able to disrupt sonic pulses, the disruption is used to determine the speed of the wind. These anemometers are able to provide very accurate measurements of wind data. They also do not involve any moving parts and thus are able to detect very minimal changes in the speed of the wind. They usually make use of four sensors that are arranged in a square pattern to be able to get accurate results.

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