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Beaufort Scale
| Force | MPH | Kn | Sea Conditions | |
| 0 | Calm | 1 | 1 | Sea like a mirror. |
| 1 | Light air | 1-3 | 1-3 | Ripples with the appearance of scales are formed, but without foam crests. |
| 2 | Light breeze | -7 | 4-6 | Small wavelets, short but more pronounced. Crests glassy but do not break. |
| 3 | Gentle breeze | 8-12 | 7-10 | Large wavelets, crests begin to break. Foam glassy, perhaps scattered white horses. |
| 4 | Moderate breeze | 13-17 | 11-16 | Small waves, becoming longer, fairly frequent white horses. |
| 5 | Fresh breeze | 18-24 | 17-21 | Moderate waves, longer, many white foam crests. Chance of some spray. |
| 6 | Strong breeze | 25-30 | 22-27 | Large waves begin to form; white foam crests more extensive everywhere, probably some spray. |
| 7 | Near gale | 31-38 | 28-33 | Sea heaps up, white foam from breaking waves begins to be blown in streaks along the direction of the wind. |
| 8 | Gale | 39-46 | 34-40 | Moderately high waves, longer, edges of crests begin to break into spindrift. Well marked streaks of foam. |
| 9 | Strong Gale | 47-54 | 41-47 | High waves, dense streams of foam. Crests begin to topple, tumble and roll over. Spray may affect visibility. |
| 10 | Storm | 55-63 | 48-55 | Very high waves, long overhanging crests. Whole surface of the sea white. Tumbling of the sea heavy and shock-like. Visibility affected. |
| 11 | Violent Storm | 64-72 | 56-63 | Exceptionally high waves. Sea completely covered with foam. Edges of crests everywhere blown into froth. Sea completely white with driving spray. |
| 12 | Hurricane | 73+ | 64+ | Air filled with foam and spray. Sea completely white with driving spray. Visibility very seriously affected. |