The wind sock is a tube-shaped flag that is used to help track wind direction and speed. One end is attached to a flag pole and the wind funnels through it, inflating the tube. If a wind sock is inflated and pointing to the north, it means the wind is coming from the south.
Wind socks are used for safety purposes at airports and chemical plants where knowing wind direction can be vital. They also can be found on farms, at schools and by the side of roads prone to heavy winds.
The wind sock is thought to be a Japanese invention, where its original use was as a celebratory decoration. Wind socks were used to announce the birth of a male child into a family. They were shaped like fish and often had the family crest on them.
