Beaufort scale
/ˈbəʊfət/- 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')蒲福风级（根据目测将风力分为0-12级）。
词源
mid 19th cent.: named after Sir Francis Beaufort （1774-1857）， the English admiral and naval hydrographer who devised it.