Understanding Wind Cup Anemometers: How to Determine Wind Direction

[voyager221]

How is it possible without knowing the wind direction to work out which direction the cups are moving (ie clockwise or anticlockwise round) simply by looking at a diagram of a wind cup anemometer? Does the wind always blow into the hollow end of a cup and then each cup moves forward and the next one takes its turn?

What does 'On an anemometer with four cups it is easy to see that since the cups are arranged symmetrically on the end of the arms, the wind always has the hollow of one cup presented to it and is blowing on the back of the cup on the opposite end of the cross' mean?

 

[Valerie Park]

It is not possible to determine the direction of movement of the cups on a wind cup anemometer simply by looking at a diagram. In order to determine the direction of movement, you would need to know the direction of the wind. Generally, the wind will blow into the hollow end of a cup and then each cup moves forward and the next one takes its turn. The statement "On an anemometer with four cups it is easy to see that since the cups are arranged symmetrically on the end of the arms, the wind always has the hollow of one cup presented to it and is blowing on the back of the cup on the opposite end of the cross" means that, since the cups are arranged in a symmetrical pattern on the arms of the anemometer, the wind will always be blowing into one cup while simultaneously blowing on the back of the cup on the opposite side of the arms. This allows the anemometer to measure the wind speed accurately.