wind

Displacement of air caused by variations in pressure between two regions of the atmosphere.

pennant

Symbol of a wind blowing between 55 and  0 m h.

barb

Symbol of a wind blowing between 9 and  4 m h.

half barb

Symbol of a wind blowing between 3 and   m h.

shaft

Symbol of a wind blowing at a speed lower than 3 mph.

wind arrow

Symbol that uses the position of the shaft to indicate wind direction and the number of barbs and pennants to indicate wind speed.

calm

Symbol indicating the absence of wind.