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Ocean in Motion: Waves - Beaufort Wind Scale

Beaufort Wind Force Wind Speed
(Knots)
WMO* Wind Classification Wave Height (ft) Sea Conditions
0 Less than 1 Calm   Sea surface is smooth and mirror-like.
1 1-3 Light Air   Scaly ripples without foam crests.
2 4-6 Light Breeze   Small wavelets with glassy appearing crests and no breaking.
3 7-10 Gentle Breeze   Large wavelets, crests begin to break and whitecaps are scattered whitecaps.
4 11-16 Moderate Breeze 1-4 Small waves becoming longer and whitecaps are numerous.
5 17-21 Fresh Breeze 4-8 Moderate waves take longer form and there are many whitecaps and some spray.
6 22-27 Strong Breeze 8-13 Larger waves form and whitecaps are common, along with more spray.
7 28-33 Near Gale 13-20 The sea heaps up and white foam streaks off breakers.
8 34-40 Gale 13-20 Moderately high waves of greater length are formed. The edges of crests begin to break into spindrift and foam blown in streaks.
9 41-47 Strong Gale 20 High waves occur, the sea begins to roll and dense streaks of foam form. Spray may reduce visibility.
10 48-55 Storm 20-30 Very high waves form with overhanging crests. The sea is white with densely blown foam. There is heavy rolling and lowered visibility.
11 56-63 Violent Storm 30-45 Exceptionally high waves form and foam patches cover the sea. Visibility is more reduced.
12 64+ Hurricane 45 Exceptionally high waves. The air is filled with foam and the sea completely white with driving spray. Visibility greatly reduced.

    * World Meteorological Organization

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