| Force |
Speed |
Speed |
Wind Description |
Sea Condition |
Wave Height |
Wave Height |
| |
miles/hr |
knots |
|
|
meters |
ft |
| |
|
|
|
|
|
|
| 0 |
0 - 1 |
0 - 1 |
Calm |
Sea like a mirror |
- |
- |
| 1 |
1 - 3 |
1 - 3 |
Light air |
Ripples with the appearance of scales are formed, but
without foam crests. |
0.1 |
1/4 |
| 2 |
4 - 7 |
4 - 6 |
Light Breeze |
Small wavelets, still short, but more pronounced.
Crests have a glassy appearance and do not break. |
0.2 - 0.3 |
0.5 - 1 |
| 3 |
8 - 12 |
7-10 |
Gentle Breeze |
Large wavelets. Crests begin to break. Foam of glassy
appearance. Perhaps scattered white horses. |
0.6 - 1 |
2 - 3 |
| 4 |
13 - 18 |
11 - 16 |
Moderate Breeze |
Small waves, becoming larger; fairly frequent white
horses. |
1 - 1.5 |
3.5 - 5 |
| 5 |
19 - 24 |
17 - 21 |
Fresh Breeze |
Moderate waves, taking a more pronounced long form;
many white horses are formed. Chance of some spray. |
2 - 2.5 |
6 - 8.5 |
| 6 |
25 - 31 |
22 - 27 |
Strong Breeze |
Large waves begin to form; the white foam crests are
more extensive everywhere. Probably some spray. |
3 - 4 |
9.5 - 13 |
| 7 |
32 - 38 |
28 - 33 |
Near Gale |
Sea heaps up and white foam from breaking waves
begins to be blown in streaks along the direction of the
wind. |
4 - 5.5 |
13.5 - 19 |
| 8 |
39 - 46 |
34 - 40 |
Gale |
Moderately high waves of greater length; edges of
crests begin to break into spindrift. The foam is blown
in well-marked streaks along the direction of the wind. |
5.5 - 7.5 |
18 - 25 |
| 9 |
47 - 54 |
41 - 47 |
Severe Gale |
High waves. Dense streaks of foam along the direction
of the wind. Crests of waves begin to topple, tumble and
roll over. Spray may affect visibility. |
7 - 10 |
23 - 32 |
| 10 |
55 - 63 |
48 - 55 |
Storm |
Very high waves with long over-hanging crests. The
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. The
'tumbling' of the sea becomes heavy and shock-like.
Visibility affected. |
9 - 12.5 |
29 - 41 |
| 11 |
64 - 72 |
56 - 63 |
Violent Storm |
Exceptionally high waves (small and medium-size ships
might be for a time lost to view behind the waves). The
sea is completely covered with long white patches of foam
lying along the direction of the wind. Everywhere the
edges of the wave crests are blown into froth. Visibility
affected. |
11.5 - 16 |
37 - 52 |
| 12 |
73 - 83 |
64 - 71 |
Hurricane |
The air is filled with foam and spray. Sea completely
white with driving spray; visibility very seriously
affected. |
14 - (-) |
45 - (-) |
