Beaufort
Force
|
Windspeed
Knots
|
Description
|
Sea Condition
|
0
|
0
|
Calm |
Sea like a mirror |
1
|
1 - 3
|
Light Air |
Ripples but without foam
crests |
2
|
4 - 6
|
Light Breeze |
Small wavelets. Crests do not
break |
3
|
7 - 10
|
Gentle Breeze |
Large wavelets. Perhaps
scattered white horses |
4
|
11 - 16
|
Moderate Breeze |
Small waves. Fairly frequent
white horses. |
5
|
17 - 21
|
Fresh Breeze |
Moderate waves, many white
horses |
6
|
22 - 27
|
Strong Breeze |
Large waves begin to form;
white foam crests, probably spray |
7
|
28 - 33
|
Near Gale |
Sea heaps up and white foam
blown in streaks along the direction of the wind |
8
|
34 - 40
|
Gale |
Moderately high waves, crests
begin to break into spindrift |
9
|
41 - 47
|
Strong Gale |
High waves. Dense foam along
the direction of the wind. Crests of waves begin to roll over. Spray may
affect visibility |
10
|
48 - 55
|
Storm |
Very high waves with long
overhanging crests. The surface of the sea takes a white appearance. The
tumbling of the sea becomes heavy and shock like. Visibility affected |
11
|
56 - 63
|
Violent Storm |
Exceptionally high waves. The
sea is completely covered with long white patches of foam lying in the
direction of the wind. Visibility affected |
12
|
64+
|
Hurricane |
The air is filled with foam
and spray. Sea completely white with driving spray. Visibility very
seriously affected. |