What is Windsock?

A windsock is a conical textile tube designed to indicate wind direction and relative wind speed. Windsocks typically are used at airports and at Petro Chemical Plants Oil and Gas . Refinery Plants.  there is risk and danger from gaseous leakage. They are sometimes located alongside highways at windy locations.

Wind direction is the opposite of the direction in which the windsock is pointing (note that wind directions are conventionally specified as being the compass point from which the wind originates; so a windsock pointing due east indicates a westly. Windspeed is indicated by the windsock's angle relative to the mounting pole;  in high win it fly horizontally and when low winds, the windsock droops.

Refer  FAA standards referenced below,

1)    15-knot (28 km/h; 17 mph) wind will fully extend the properly functioning windsock.

2)     A 3-knot (5.6 km/h; 3.5 mph) breeze will cause the properly functioning windsock to orient itself according to the wind.

At many airports, windsocks are lighted at night, either by flood lights on top surrounding it or with one mounted on the pole shining inside it.

Windsocks are also popular with children and can have bright and colourful designs or make windsock flag. These windsocks are not particularly functional and mostly for decoration, however they can be used as a basic guide to wind direction and speed. You can buy winsocks from wind sock suppliers .

Info from Wikipedia