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Beaufort Wind Scale

Sir Francis Beaufort (1774–1857), a captain in the British Admiralty created the first version of his famous wind scales in 1806 for his own use. The Sea Conditions column describes observations used by mariners to estimate wind speeds since, prior to the advent of GPS, obtaining precise speeds from a (possibly) moving vessel was impossible.












Beaufort NumberWind speedDescriptionWave HeightSea ConditionsLand Conditions
ktkm/hmphm/sm/ft
00000-0.2Calm0/0FlatCalm, smoke rises vertically
11-31-61-30.3-1.5Light Air0.1/0.33Ripples without crestsWind motion visible in smoke
24-67-114-71.6-3.3Light
Breeze
0.2/0.66Small wavelets, crests of glassy appearance, not breakingWind felt on exposed skin, leaves rustle
37-1012-198-123.4-5.4Gentle
Breeze
0.6/2Large wavelets, crests begin to break, scattered whitecapsLeaves and smaller twigs in constant motion
411-1620-2913-185.5-7.9Moderate
Breeze
1/3.3Small wavesDust and loose paper raised. Small branches begin to move.
517-2130-3919-248.0-10.7Fresh
Breeze
2/6.6Moderate (1.2 m) longer waves, some foam and spraySmaller trees sway
622-2740-5025-3110.8-13.8Strong
Breeze
3/9.9Large waves with foam crests and some sprayLarge branches in motion, whistling heard in overhead wires, umbrella use becomes difficult
728-3351-6232-3813.9-17.1Near
Gale
4/13.1Sea heaps up and foam begins to streakWhole trees in motion, effort needed to walk against the wind
834-4063-7539-4617.2-20.7Gale5.5/18Moderately high waves with breaking crests forming spindrift, streaks of foamTwigs broken from trees, cars veer on road
941-4776-8747-5420.8-24.4Strong
Gale
7/23High waves (2.75 m) with dense foam, wave crests start to roll over, considerable sprayLight structure damage
1048-5588-10255-6324.5-28.4Storm9/29.5Very high waves, sea surface is white with considerable tumbling, visibility reducedTrees uprooted. Considerable structural damage
1156-63103-11764-7228.5-32.6Violent
Storm
11.5/37.7Exceptionally high wavesWidespread structural damage
12>63>117>72>32.7Hurricane14+/46+Huge waves, air filled with foam and spray, sea completely white with driving spray, visibility very greatly reducedMassive and widespread damage to structures

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