A windsock (also known as wind cone or wind sleeve) is a conical textile tube that resembles a giant

sock A sock is a piece of clothing worn on the feet and often covering the ankle or some part of the Calf (leg), calf. Some types of shoes or boots are typically worn over socks. In ancient times, socks were made from leather or matted animal hair. ...

. It can be used as a basic indicator of

wind speed In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Wind speed is now commonly measured with an anemometer. Wind spe ...

and direction, or as decoration. Windsocks are typically used at airports to show the direction and strength of the wind to pilots, and at chemical plants where there is risk of gaseous leakage. They are also sometimes located alongside highways at windy locations. At many airports, windsocks are externally or internally lit at night.

Wind direction Wind direction is generally reported by the direction from which the wind originates. For example, a ''north'' or ''northerly'' wind blows from the north to the south; the exceptions are onshore winds (blowing onto the shore from the water) and ...

is opposite the direction in which the windsock is pointing. Wind speed is indicated by the windsock's angle relative to the mounting polein low winds it droops; in high winds, it flies horizontally.

Design

Alternating stripes of high-visibility orange and white were initially used to help estimate wind speed, with each stripe extended adding 3

knots A knot is a fastening in rope or interwoven lines. Knot or knots may also refer to: Other common meanings * Knot (unit), of speed * Knot (wood), a timber imperfection Arts, entertainment, and media Films * ''Knots'' (film), a 2004 film * ''Kn ...

(5.6km/h; 3.5mph) to the estimated speed. Some circular frame mountings cause windsocks to be held open at one end and the first stripe extended, indicating a velocity of 3 knots even when stripes are not present. A fully extended windsock suggests a wind speed of or greater.

Standards

Per FAA standards, a properly functioning windsock orients itself to a breeze of at least and fully extends in a wind of . Per

Transport Canada Transport Canada () is the Ministry (government department), department within the Government of Canada responsible for developing regulations, Policy, policies and Public services, services of road, rail, marine and air Transport in Canada, tra ...

standards, a 15-knot wind fully extends the windsock; a wind raises it to 5° below the horizontal; and a wind raises it to 30° below the horizontal.

ICAO The International Civil Aviation Organization (ICAO ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international sch ...

standards specify a truncated cone-shaped windsock at least long and in diameter at the large end. It should be readable from an altitude of and ideally be of a single colour. If it is necessary to use two colours, they should ideally be orange and white, arranged in five alternating bands, with the first and last darker in tone. In wind speeds of or more, they must indicate wind direction to within ±5°.

Other related wind direction indicators

Wind tees and wind

tetrahedron In geometry, a tetrahedron (: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex (geometry), vertices. The tet ...

s are two other commonly used wind direction indicators in airports. Wind tees are shaped like an airplane so that they match with the heading of an aircraft ready to take off and land. Wind tetrahedrons always have their pointed ends pointing to the wind. Wind tees and tetrahedrons can swing freely and align themselves with the wind direction, but neither provides an indication of wind speed, unlike a windsock. Since a wind tee or tetrahedron can also be manually set to align with the runway in use, a pilot should also look at the wind sock for wind information, if one is available.

Notes

References

{{Authority control Airport infrastructure Meteorological instrumentation and equipment Socks

Design

Standards

Other related wind direction indicators

See also

Notes

References