| Beaufort
|
Speed |
Sea
State |
On Land |
| Force |
Description |
knots |
km/h |
mph |
| 0 |
Calm |
Less
than 1 |
Less
than 1 |
Less
than 1 |
Sea
like a mirror |
Smoke
rises vertically. |
| 1 |
Very
Light |
1-3 |
1-5 |
1-3 |
Ripples
with appearance of scales, no form crests |
Direction
of wind shown by smoke drift but not by wind vanes. |
| 2 |
Light
breeze |
4-6 |
6-11 |
4-7 |
Wavelets,
small but pronounced. Crests with glassy appearance, but do
not break. |
Wind
felt on face , leaves rustle, ordinaryt wind vane moved by
wind. |
| 3 |
Gentle
breeze |
7-10 |
12-19 |
8-12 |
Large
wavelets, crests begin to break. Glassy looking foam,
occasional white horses. |
Leaves
and small twigs in constant motion, wind extends white flag. |
| 4 |
Moderate
breeze |
11-16 |
20
- 29 |
13
- 18 |
Small
waves becoming longer, frequent white horses. |
Wind
raises dust and loose paper, small branches move. |
| 5 |
Fresh
breeze |
17
- 21 |
30
- 39 |
19
- 24 |
Moderate
waves of pronounced long form. Many whit horses, some spray. |
Small
trees in leaf start to sway, crested wavelets on inland
waters. |
| 6 |
Strong
breeze |
22
- 27 |
40
- 50 |
25
- 31 |
Some
large waves, extensive white foam crests, some spray. |
Large
branches in motion, whistling in telegraph wires, umberellas
used with difficulty. |
| 7 |
Near
gale |
28
- 33 |
51
- 61 |
32
- 38 |
Sea
heaped up, white foam from breaking waves blowing in streaks
with the wind. |
Whole
trees in motion, inconvient to walk against wind. |
| 8 |
Gale |
34
- 40 |
62
- 74 |
39
- 46 |
Moderately
high and long waves. Crests break into spin drift, blowing
foam in well marked streaks. |
Twigs
break from trees, difficult to walk. |
| 9 |
Strong
gale |
41
- 47 |
75
- 87 |
47
- 54 |
High
waves, dense foam streaks in wind, wave crests topple,
tumble and roll over. Spray reduces visability. |
Slight
structural damage occuers, chimney pots and slates removed. |
| 10 |
Storm |
48
- 55 |
88
- 101 |
55
- 63 |
Very
high waves with long overhanging crests. Dence blowing foam,
sea surface appears white. Heavy tumbling of sea,
shock-like, poor visability. |
Trees
uprooted, considerable structural damage occurs. |
| 11 |
Violent
storm |
56
- 63 |
102
- 117 |
64
- 73 |
Exceptionally
high waves, sometimes concealing small and medium sized
ships. Sea comletely covered with long white patches of
foam. Edges of wave crests blown into froth . Poor
visability. |
Widespread
damage. |
| 12 |
Hurricane |
>64 |
>119 |
>74 |
Air
filled with foam and spray, sea white with driving spray,
visability. |
Widespread
damage. |
