Beaufort Scale Of Wind
Descriptions of the various ranks in the Beaufort scale of wind are listed in the table.
The Beaufort scale of wind (nautical) | ||||
---|---|---|---|---|
Beaufort number | name of wind | wind speed | description of sea surface | |
knots | kph | |||
0 | calm | <1 | <1 | sea like a mirror |
1 | light air | 1–3 | 1–5 | ripples with appearance of scales are formed, without foam crests |
2 | light breeze | 4–6 | 6–11 | small wavelets still short but more pronounced; crests have a glassy appearance but do not break |
3 | gentle breeze | 7–10 | 12–19 | large wavelets; crests begin to break; foam of glassy appearance; perhaps scattered white horses |
4 | moderate breeze | 11–16 | 20–28 | small waves becoming longer; fairly frequent white horses |
5 | fresh breeze | 17–21 | 29–38 | moderate waves taking a more pronounced long form; many white horses are formed; chance of some spray |
6 | strong breeze | 22–27 | 39–49 | large waves begin to form; the white foam crests are more extensive everywhere; probably some spray |
7 | moderate gale (or near gale) | 28–33 | 50–61 | sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind; spindrift begins to be seen |
8 | fresh gale (or gale) | 34–40 | 62–74 | moderately high waves of greater length; edges of crests break into spindrift; foam is blown in well-marked streaks along the direction of the wind |
9 | strong gale | 41–47 | 75–88 | high waves; dense streaks of foam along the direction of the wind; sea begins to roll; spray affects visibility |
10 | whole gale (or storm) | 48–55 | 89–102 | very high waves with long overhanging crests; resulting foam in great patches is blown in dense white streaks along the direction of the wind; on the whole the surface of the sea takes on a white appearance; rolling of the sea becomes heavy; visibility affected |
11 | storm (or violent storm) | 56–63 | 103–114 | exceptionally high waves; small- and medium-sized ships might be for a long time lost to view behind the waves; sea is covered with long white patches of foam; everywhere the edges of the wave crests are blown into foam; visibility affected |
12–17 | hurricane | 64 and above | 117 and above | the air is filled with foam and spray; sea is completely white with driving spray; visibility very seriously affected |
Beaufort number | sea disturbance number | average wave height |
||
ft | m | |||
0 | 0 | 0 | 0 | |
1 | 0 | 0 | 0 | |
2 | 1 | 0–1 | 0–0.3 | |
3 | 2 | 1–2 | 0.3–0.6 | |
4 | 3 | 2–4 | 0.6–1.2 | |
5 | 4 | 4–8 | 1.2–2.4 | |
6 | 5 | 8–13 | 2.4–4 | |
7 | 6 | 13–20 | 4–6 | |
8 | 6 | 13–20 | 4–6 | |
9 | 6 | 13–20 | 4–6 | |
10 | 7 | 20–30 | 6–9 | |
11 | 8 | 30–45 | 9–14 | |
12–17 | 9 | over 45 | over 14 |