|meteorol an international scale of wind velocities ranging for practical purposes from 0 (calm) to 12 (hurricane force). In the US an extension of the scale, from 13 to 17 for winds over 64 knots, is used|
|[C19: after Sir Francis Beaufort (1774--1857), British admiral and hydrographer who devised it]|
|Beaufort scale (bō'fərt) Pronunciation Key
A scale for classifying the force of the wind, ranging from 0 (calm) to 12 (hurricane). A wind classified as 0 has a velocity of less than 1.6 km (1 mi) per hour; a wind classified as 12 has a velocity of over 119 km (74 mi) per hour. Other categories include light air, five levels of breeze, four levels of gale, and storm. The scale was devised in 1805 as a means of describing the effect of different wind velocities on ships at sea. It is named after an admiral in the British navy, Sir Francis Beaufort (1774-1857).