The Beaufort Scale - Eurochron EFWS2900 Notice D'emploi

15. The Beaufort scale

The Beaufort scale is an empirical scale for estimating the wind speed without using measuring instruments. It works
by relating wind speed to observed conditions on sea or land, such as the movement of trees or waves on the surface
of the ocean. It was named after Sir Francis Beaufort. The wind speed on land and sea is calculated in different
ways. The anemometer displays measurements on the Beaufort scale from 0-12 using a bar graph. The table below
provides an approximate conversion of Beaufort measurements into different units.
Beaufort scale
0 Calm
1 Light air
2 Light breeze
3 Gentle
breeze
4 Moderate
breeze
5 Fresh breeze
6 Strong
breeze
7 Near gale
8 Gale
9 Strong gale
10 Storm
11 Violent storm
12 Hurricane
force
60
m/s kts
0 - 0.2 0 - 1
0.3 - 1.5 1 - 3
1.6 - 3.3 4 - 6
3.4 - 5.4 7 - 10
5.5 - 7.9 11 - 16
8.0 - 10.7 17 - 21
10.8 - 13.8 22 - 27
13.9 - 17.1 28 - 33
17.2 - 20.7 34 - 40
20.8 - 24.4 41 - 47
24.5 - 28.4 48 - 55
28.5 - 32.6 56 - 63
32.6 >63
mph km/h
0 - 1 0 - 1
1 - 3 1 - 5
4 - 7 6 - 11
8 - 12 12 - 19
13 - 18 20 - 28
19 - 24 29 - 38
25 - 31 39 - 49
32 - 38 50 - 61
39 - 46 62 - 74
47 - 54 75 - 88
55 - 63 89 - 102
64 - 72 103 - 117
>72 >117
ft/min
0 - 58
59 - 314
315 - 668
669 - 1082
1083 - 1574
1575 - 2125
2126 - 2735
2736 - 3385
3386 - 4093
4094 - 4822
4823 - 5609
5610 - 6417
>6417