18m Anemometer
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The 18m Anemometer is mounted 18m above the ground on a met tower (Twr 4).
About Anemometers
The 18m Anemometer is mounted 18m above the
ground, on the same tower as the 18m Wind Vane.
A cup anemometer is used to measure wind speed. As the wind blows the cups rotate and so spin the vertical spindle – the faster the wind is blowing the faster the spindle turns. The instrument output consists of pulses and these can be counted during a sample interval, to measure the average wind speed. The manufacturer is Vector Instruments.
Cup anemometers do not measure low wind speeds very accurately and indeed at very low wind speed do not turn at all and thus give a false reading of zero. They do not give accurate readings when it is very cold (as the spindle can freeze up) or during snow (as the cups can fill up with snow).
Wind speed is measured by the ERU met station in metres per second (m/s). Other units used include miles per hour (used in Met Office forecasts), and knots (nautical miles per hour, used by sailors).
As an approximation you can double the m/s value to get the equivalent mph figure (for example 10m/s = 22.4mph)
Weatheronline has an online wind speed converter for conversion between various units. This Met Office table shows wind speed measured in various units, including miles per hour and knots.
The Beaufort scale is used in Met Office marine forecasts as an empirical measure for describing wind intensity based on observed sea conditions (for example “Storm Force 10”), as shown in the Met Office table. This Royal Meteorological Society table does the same for observed land conditions. A full description of the Beaufort scale is here.
There are two sets of instruments, but one is dedicated to an adjacent experimental setup.
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