Windrose

Windrose shows the frequency of wind direction in a given area. Generally, given as a percentage of how much the wind has blown in the direction.

The graph shown is a Windrose of Heathrow in England. The wind blows mostly from the South-Southwest, and the least from the South-Southeast and Southeast. The change in color between yellow and blue show the change in the interval.

http://www.metoffice.gov.uk/climate/uk/so/print.html