|
Beaufort Force
|
Description
|
Specification on land
|
Speed
knots km/h mph
|
| 0 |
Calm |
Smoke rises vertically. |
Less than 1 |
Less than 1 |
Less than 1 |
| 1 |
Very Light |
Direction of wind shown by smoke drift but not by wind vanes. |
1 - 3 |
1 - 5 |
1 - 3 |
| 2 |
Light breeze |
Wind felt on face, leaves rustle, ordinary wind vane moved by wind. |
4 - 6 |
6 - 11 |
4 - 7 |
| 3 |
Gentle breeze |
Leaves and small twigs in constant motion, wind extends white flag. |
7 - 10 |
12 - 19 |
8 - 12 |
| 4 |
Moderate breeze |
Wind raises dust and loose paper, small branches move. |
11 - 16 |
20 -29 |
13 - 18 |
| 5 |
Fresh breeze |
Small trees in leaf start to sway, crested wavelets on inland waters. |
17 - 21 |
30 39 |
19 - 24 |
| 6 |
Strong breeze |
Large branches in motion, whistling in telegraph wires, umbrellas used with difficulty. |
22 - 27 |
40 - 50 |
25 - 31 |
| 7 |
Near gale |
Whole trees in motion, inconvenient to walk against wind. |
28 - 33 |
51 - 61 |
32 - 38 |
| 8 |
Gale |
Twigs break from trees, difficult to walk. |
34 - 40 |
62 - 74 |
39 - 46 |
| 9 |
Strong gale |
Slight structural damage occurs, chimney pots and slates removed. |
41 - 47 |
75 - 87 |
47 - 54 |
| 10 |
Storm |
Trees uprooted, considerable structural damage occurs. |
48 - 55 |
88 - 101 |
55 - 63 |
| 11 |
Violent storm |
Widespread damage. |
56 - 63 |
102 - 117 |
64 - 73 |
| 12 |
Hurricane |
Widespread damage. |
>64 |
>119 |
>74 |