A symbol used for station plots on a synoptic chart to indicate wind direction and strength. The symbol consists of a shaft, drawn upwind of the station symbol, its direction representing the wind direction to the nearest 10°. At the outer end of the shaft, feathers (also known as barbs) or pennants are added to indicate wind speed. Modern plots show speeds in multiples of 5 knots. A feather consists of a short oblique stroke at the far end of the shaft, drawn on the side nearest low pressure (i.e. on the left looking towards the station in the northern hemisphere, and on the right in the southern—see Buys Ballot's Law). A half-length feather indicates 5 knots; a full-length one 10 knots; and a pennant (a small triangular ‘flag’) is used for 50 knots. Originally a half-length feather indicated a Beaufort force of 1 (see Beaufort Scale), and a full feather a Beaufort force of 2. The term ‘barb’ is the commonly used form in North America.
Subjects: Meteorology and Climatology.