Beaufort Scale Number |
Wind Speed |
Wind Name | Observable Wind Characteristics | ||
m/sec | mph | kph | |||
0 | 1 | under 1 | under 1 | Calm | Smoke rises vertically |
1 | 1 | 1-3 | 1-5 | Light air | Wind direction shown by smoke drift but not by wind vanes |
2 | 2 | 4-7 | 6-11 | Light breeze | Wind felt on face; leaves rustle; wind vanes move |
3 | 4 | 8-12 | 12-19 | Gentle breeze | Leaves and small twigs in constant motion; wind extends a light flag |
4 | 7 | 13-18 | 20-28 | Moderate | Dust and loose paper raised; small branches moved |
5 | 10 | 19-24 | 29-38 | Fresh | Small trees in leaf begin to sway; crested wavelets on inland waters |
6 | 12 | 25-31 | 39-49 | Strong | Large branches in motion; difficulty in using umbrellas; whistling heard in telegraph wires |
7 | 15 | 32-38 | 50-61 | Near gale | Whole trees in motion; inconvenience in walking against wind |
8 | 18 | 39-46 | 62-74 | Gale | Twigs broken off trees; progress impeded |
9 | 20 | 47-54 | 75-88 | Strong gale | Slight structural damage occurs |
10 | 26 | 55-63 | 89-102 | Storm | Trees uprooted; considerable damage occurs |
11 | 30 | 64-72 | 103-117 | Violent storm | Widespread damage occurs |
12-17 | over 33 | over 73 | over 118 | Hurricane |
Sea Disturbance Number | Average Wave Height | Observable Sea Characteristics | |
ft | m | ||
0 | 0 | 0 | Sea like a mirror |
0 | 0 | 0 | Ripples like scales without foam crests |
1 | 0-1 | 0.3 | More definite wavelets; crests do not break |
2 | 1-2 | 0.3-0.6 | Large wavelets; crests begin to break; scattered white horses |
3 | 2-4 | 0.6-1.2 | Small waves become longer; fairly frequent white horses |
4 | 4-8 | 1.2-2.4 | Moderate waves with a more definite long form; many white horses; some spray possible |
5 | 8-13 | 2.4-4 | Large waves form; more extensive white foam crests; some spray probable |
6 | 13-20 | 4-6 | Sea heaps up; streaks of white foam blown along |
6 | 13-20 | 4-6 | Moderately high waves of greater length; well-marked streaks of foam |
6 | 13-20 | 4-6 | High waves; dense streaks of foam; sea begins to roll; spray affects visibility |
7 | 20-30 | 6-9 | Very high waves with long overhanging crests; dense streaks of foam blown along;generally white appearance of surface; heavy rolling |
8 | 30-45 | 9-14 | Exceptionally high waves; long white patches of foam; poor visibility; ships lost to view behind waves |
9 | over 45 | over 14 | Air filled with foam and spray; sea completely white; poor visibility |
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