Anemometer Wind Gauge
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Anemometer Wind Gauge
The anemometer is derived from the Greek word "anemos", meaning wind, and allows you to measure the wind speed and wind direction. Wind direction and speed are key measurements in weather forecasting. In personal weather stations you will usually find one of two anemometer types: Cup or Windmill.
The simplest type of Anemometer is the Cup Anemometer which was invented in 1846 by Dr. John Thomas Romney Robinson. This first anemometer consisted of 4 cups mounted on equally distanced horizontal shafts which rotated on a central vertical shaft. The cups caught the air flowing past which caused the cups to rotate the shaft. Counting the shaft revolutions, you could calculate wind speed. The cup anemometer was improved in several times in recent history with its recent incarnation as a 3 cup anemometer. The latest 3 cum anemometer has an error rate of less then 3% up to 60mph and with an enhancement made by Australian Derek Weston can also measure wind direction. Derek Weston added a tag to one of the 3 cups which causes the cupwheel speed to increase and decrease as the tag moves alternately with and against the wind. Wind direction is calculated from these cyclical changes in cupwheel speed, while wind speed is as usual determined from the average cupwheel speed.
The windmill, also called the propeller anemometer, is another type of mechanical velocity anemometer you will find with home weather stations. The windmill anemometer uses a wind vane to keep the propeller of the anemometer facing the incoming wind. An Aerovane combines a propeller and tail on the same axis as one flowing piece to accurately measure wind speed and direction.
One of the newer anemometers on the market today is the Hot-Wire Anemometer. This anemometer sensor has no moving parts. The main component of the Hot-Wire Anemometer a very thin wire, usually Tungsten, which is heated to just above ambient temperature. The sensor measures the cooling effect of the air flow passing over the heated wire. The measurement is a complex calculation based on the electrical conductivity of the metal wire at various temperatures. This measurement is so precise that this same sensor is also used in new automobiles named mass airflow sensor which feeds air intake information to the cars computer to regulate fuel and other functions. The Hot-Wire anemometer is not mainstream in current home weather stations, but worth mentioning as something we may see in the near future.