Air

The anemometer

Wind speed is expressed in km/h or knots (1 knot = 1.852 km/h), or, more rarely in meteorology, with the Beaufort scale (proposed in 1805 by the English Admiral Francis Beaufort, to classify the winds according to their intensity). Anemoscopes measure the direction of the wind and consist of simple metal vanes that rotate on a pivot and align with the direction of the wind (like the weathercocks on the roofs of houses or windsocks in the airports, that also provide an estimate of the speed of the wind depending on how the sock expands). A special instrumentation allows automatic recording of the data. Anemometers instead enable measurement of the wind speed with a small “pinwheel” that spins at a speed that is proportional to the speed of the wind. Generally, anemoscopes and anemometers are coupled in the same instrument. The more modern models are electric and special transmitters enable the transmission of data in real time to the processing station.