Beaufort Wind Scale

Devised by British Rear-Admiral, Sir Francis Beaufort in 1805
based on observations of the effects of the wind
Beaufort
number
(force)
Wind SpeedWave
height
(feet)
WMO*
description
Effects observed on the seaEffects observed on land
knotsmph
0under 1under 1-CalmSea is like a mirror
11 - 31 - 30.25Light airRipples with appearance of scales; no foam crests
24 - 64 - 70.5 - 1Light breezeSmall wavelets; crests of glassy appearance, not breaking
37 - 108 - 122 - 3Gentle breezeLarge wavelets; crests begin to break; scattered whitecaps
411-1613-183½ - 5Moderate breezeSmall waves, becoming longer; numerous whitecaps
517-2119-246 - 8Fresh breezeModerate waves, taking longer form; many whitecaps; some spray
622-2725-319½-13Strong breezeLarger waves forming; whitecaps everywhere; more spray
728-3332-3813½-19Near galeSea heaps up; white foam from breaking waves begins to be blown in streaks
834-4039-4618-25GaleModerately high waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks
941-4747-5423-32Strong galeHigh waves; sea begins to roll; dense streaks of foam; spray may begin to reduce visibility
1048-5555-6329-41StormVery high waves with overhanging crests; sea takes white appearance as foam is blown in very dense streaks; rolling is heavy and visibility is reduced
1156-6364-7237-52Violent stormExceptionally high waves; sea covered with white foam patches; visibility further reduced
1264 and over73 and over45 and overHurricaneAir filled with foam; sea completely white with driving spray; visibility greatly reduced
* World Meteorological Organization

Fujita Scale of Tornado Intensity

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