Beaufort Scale
|
Wind
|
Speed |
|
|
Probable |
Wave Height |
Force |
Knots |
MPH |
Description |
|
Metres |
Feet |
0 |
0 |
0 |
Calm |
Sea like a mirror. |
0 |
0 |
1 |
1-3 |
1-3 |
Light Air |
Ripples with the appearance of scales are
formed but without foam. |
0 |
0 |
2 |
4-6 |
4-7 |
Light Breeze |
Small wavelets, still short but more
pronounced. Crests have a
glassy appearance and do not break. |
.1 |
.3 |
3 |
7-10 |
8-11 |
Gentle Breeze |
Large wavelets, crests begin to break; foam of
glassy appearance, perhaps scattered white
horses. |
.4 |
1.5 |
4 |
11-16 |
12-18 |
Moderate Breeze |
Small waves becoming longer; fairly frequent
white horses. |
1 |
3 |
5 |
17-21 |
19-24 |
Fresh Breeze |
Moderate waves taking a more pronounced long
form; many white horses, chance of some
spray. |
2 |
6 |
6 |
22-27 |
25-31 |
Strong Breeze |
Large waves begin to foam and white foam crests
become more extensive, probably some spray. |
3 |
10 |
7 |
28-33 |
32-38 |
Near Gale |
Sea heaps up and white foam from the breaking
waves begins to be blown in streaks. |
4 |
14 |
8 |
34-40 |
39-46 |
Gale |
Moderately high waves of greater length, edges
of crests begin to break into spindrift. The foam blown in
well-marked streaks. |
5.5 |
18 |
9 |
41-47 |
47-54 |
Strong |
High waves; dense streaks of foam. Crests begin to topple and roll
over, spray may effect
visibility. |
7 |
25 |
10 |
48-55 |
55-63 |
Storm |
Very high waves with long, overhanging
crests. Foam in great patches
is blown in dense white streaks making surface of the sea white. The tumbling of the sea becomes
very heavy and shock-like.
Visibility is poor. |
9 |
30 |
11 |
56-63 |
64-72 |
Violent Storm |
Exceptionally high waves; the sea is completely
covered with patches of foam.
Visibility is reduced. |
11 |
36 |
12 |
64+ |
73+ |
Hurricane |
The air is filled with foam and spume; sea
completely white with driving spray, visibility very seriously
affected. |
14 |
47 |