It was introduced in 1806 by Admiral Sir Francis Beaufort (1774 - 1857) of the British navy.

Beaufort
Bf.

Avg
km/h

Knots

Meters/sec

1
(light air)

3,2

1 - 3

0,3 - 1,5

2
(light breeze)

9

4 - 6

1,6 - 3,3

3
(gentle breeze)

16

7 - 10

3,4 - 5,4

4
(moderate breeze)

24

11 - 16

5,5 - 7,9

5
(fresh breeze)

34

17 - 21

8,0 - 10,7

6
(strong breeze)

44

22 - 27

10,8 - 13,8

7
(moderate gale)

56

28 - 33

13,9 - 17,1

8
(fresh gale)

68

34 - 40

17,2 - 20,7

9
(strong gale)

81

41 - 47

20,8 - 24,4

10
(whole gale)

95

48 - 55

24,5 - 28,4

11
(storm)

110

56 - 63

28,5 - 32,6

12
(hurricane)

125

64 +

32,7 - 36,9

1 knot = 1.852 km/h, or 1.150 mi/h.

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