What is the Beaufort Scale?

The Beaufort Scale used to describe wind strength and its effects on both land and sea. Below is a table detailing the different Forces and their description and their affect on the sea.

Beaufort Force Description Sea State
Speed (mph)
0 Calm Sea like a mirror
< 1
1 Very Light Ripples with appearance of scales, no foam crests
1 - 3
2 Light breeze Wavelets, small but pronounced. Crests with glassy appearance, but do not break.
4 -7
3 Gentle breeze Large wavelets, crests begin to break. Glassy looking foam, occasional white horses.
8 - 12
4 Moderate breeze Small waves becoming longer, frequent white horses.
13 - 18
5 Fresh breeze Moderate waves of pronounced long form. Many white horses, some spray.
19 - 24
6 Strong breeze Some large waves, extensive white foam crests, some spray.
25 - 31
7 Near gale Sea heaped up, white foam from breaking waves blowing in streaks with the wind.
32 - 38
8 Gale Moderately high and long waves. Crests break into spin drift, blowing foam in well marked streaks.
39 - 46
9 Strong gale High waves, dense foam streaks in wind, wave crests topple, tumble and roll over. Spray reduces visability.
47 - 54
10 Storm Very high waves with long overhanging crests. Dense blowing foam, sea surface appears white. Heavy tumbling of sea, shock-like, poor visability.
55 - 63
11 Violent storm Exceptionally high waves, sometimes concealing small and medium sized ships. Sea completely covered with long white patches of foam. Edges of wave crests blown into froth . Poor visibility.
64 - 73
12 Hurricane Air filled with foam and spray, sea white with driving spray, poor visibility.


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