windsock
Windsock at a gliding site
Windsock as a decorative object
A windsock is a tapered tube, usually made of weather-resistant nylon fabric, open at both ends. It is suspended on a mast several meters above the ground and pivoted. It is inflated by the wind and rotated so that the smaller end points downwind. The windsock thus indicates the wind direction and approximate wind speed.
Mission
Windsocks are used wherever obtaining precise data is less important than providing an easily interpretable, quickly understandable display. To avoid accidents, it is crucial, especially in hectic situations, to be able to determine the wind speed and direction at a glance. If the windsock hangs limply, there is no detectable wind. If it is firmly horizontal, there is a strong wind.
Most windsocks are divided into bright red and white rings, clearly visible in color. This not only makes them easier to spot from a distance or from the air, but also allows for a rough estimate of wind speed. A common rule of thumb is that for each inflated ring, approximately five knots of wind force are recorded.
More accurate wind measuring devices are wind direction indicators and anemometers.
aviation
Mobile windsock during firefighting operations with a helicopter
According to the rules of the International Civil Aviation Organization (ICAO), wind direction indicators must be present at all airfields and helipads. They should be clearly visible from the air and for pilots on the ground, and they should also be illuminated for visual flight at night. A windsock must not be affected by small-scale air currents (e.g., from engines) or air turbulence caused by buildings or vegetation. For easier identification from the air, each windsock should be surrounded by a circle, preferably white.
Road traffic
Windsocks can also be found on numerous roads and bridges where crosswinds can pose a serious hazard. They allow drivers to adjust their driving style in a timely manner to prevailing wind conditions, such as a sudden increase in crosswinds on viaducts. Windsocks are also used in ports, at transfer stations and fueling facilities, and in industry.