The Beaufort Scale, used throughout the marine world, has developed over many years since it was first devised by Admiral Francis Beaufort in 1806. Today, the Beaufort scale is defined for seamen in terms of sea state. It's emphasis is more on the observed effect of the wind, rather than the actual wind speed.
|Beaufort Force||Wind Speed Knots||Description||Sea Condition|
|0||0||Calm||Sea like a mirror|
|1||1 - 3||Light air||Ripples but without foam crests|
|2||4 - 6||Light breeze||Small wavelets. Crests do not break|
|3||7 - 10||Gentle breeze||Large wavelets. Perhaps scattered white horses|
|4||11 - 16||Moderate breeze||Small waves. Fairly frequent white horses|
|5||17 - 21||Fresh breeze||Moderate waves. Many white horses|
|6||22 - 27||Strong breeze||Large waves begin to form; white foam crests. Probably spray|
|7||28 - 33||Near gale||Sea heaps up and white foam blown in streaks along the direction of the wind|
|8||34 - 40||Gale||Moderately high waves. Crests begin to break into spindrift. The foam is blown in well marked streaks along the direction of the wind|
|9||41 - 47||Severe gale||High waves. Dense foam along the direction of the wind. Crests of waves begin to roll over. Spray may affect visibility|
|10||48 - 55||Storm||Very high waves with long overhanging crests. The surface of the sea takes a white appearance. The tumbling of the sea becomes heavy and shock-like. Visibility affected|
|11||56 - 63||Violent storm||Exceptionally high waves. The sea is completely covered with long white patches of foam lying in the direction of the wind. Visibility affected|
|12||64+||Hurricane||The air is filled with foam and spray. Sea completely white with driving spray. Visibility very seriously affected|
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