"Beaufort wind force" is an index assigned on the Beaufort wind force scale and relates a qualitative description of the degree of disturbance or destruction caused by wind to the speed of the wind. The Beaufort wind scale varies between 0 (qualitatively described as calm, smoke rises vertically, sea appears glassy) (wind speeds in the range 0 - 0.2 m s-1) and 12 (hurricane, wave heights in excess of 14 m) (wind speeds in excess of 32.7 m s-1).