Beaufort scale

 
Pronunciation: /ˈbəʊfət/

noun

  • a scale of wind speed based on a visual estimation of the wind’s effects, ranging from force 0 (less than 1 knot or 1 kph, ‘calm’) to force 12 (64 knots or 118 kph and above, ‘hurricane’).

Origin:

mid 19th century: named after Sir Francis Beaufort (1774–1857), the English admiral and naval hydrographer who devised it