Measurement of Surface Wind

At an airport, the wind is measured by placing the sensors 10 metres above an even-ground surface. This prevents false readings caused by surges due to ground obstacles or uneven ground. The wind vane is a simple device giving direction as shown in the figure below.

This basic instrument employed in wind speed measurement is the cup anemometer. It is placed at a height above ground level, where it will be exposed to the tree stream at the air. Its rotational speed is directly proportional to the wind speed. Its axis, the rotation of which drives a generator, and the voltage so generated, cause an electrically induced needle.