Wind force Beaufort Scale
The waves probable height shows the expectable conditions of the open sea, very far from the coasts. It should never be used in opposite sense to estimate or signal the sea state. Please remember that in internal seas and near the coasts with land winds, the waves will be lower and less steep.
|
Description term |
Wind speed |
Effect of the wind
on the sea |
| |
|
m/sec |
knots |
(offshore) |
| 0 |
Calma
Calm
Calme
Calma | 0 - 0,2 |
up to 1 |
The sea is smooth as a glass and smoke rises vertically |
| 1 |
Bava di vento
Light air
Très légère brise
Ventolina | 0,3 - 1,5 |
1 - 3 |
Slight ripples on the surface, similar to fish scales. No white crests of foam yet. |
| 2 |
Brezza leggera
Light breeze
Légère brise
Flojito, Brisa muy débil | 1,6 - 3,3 |
4 - 6 |
Small but pronounced wavelets. Crests do not break yet, but look glassy. |
| 3 |
Brezza tesa
Gentle breeze
Petit brise
Flojo, Brisa débil | 3,4 - 5,4 |
7 - 10 |
Large Wavelets whose crests start breaking, producing glassy foam. Possible scattered white horses. |
| 4 |
Vento moderato
Moderate breeze
Jolie brise
Bonancible, Brisa moderada | 5,5 - 7,9 |
11 - 16 |
Wavelets tend to become longer. Fairly frequent white horses. |
| 5 |
Vento teso
Fresh breeze
Bonne brise
Fresquito, Brisa fresca | 8,0 - 10,7 |
17 - 21 |
Moderate long waves. Many white horses, some spray possible. |
| 6 |
Vento fresco
Strong breeze
Vent frais
Fresco, Brisa fuerte | 10,8 - 13,8 |
22 - 27 |
Large waves (rollers) with white foam crests. Probably some spray. |
| 7 |
Vento forte
Near gale
Grand frais
Frescachó, Viento fuerte | 13,9 - 17,1 |
28 - 33 |
Rollers get bigger. White foam from breaking waves blows in streaks with the wind. |
| 8 |
Burrasca
Gale
Coup de vent
Viento duro | 17,2 - 20,7 |
34 - 40 |
Waves moderately high and long. Crests break into spin drift, blowing foam in well-marked streaks. |
| 9 |
Burrasca forte
Strong gale
Fort coup de vent
Viento muy duro | 20,8 - 24,4 |
41 - 47 |
High waves with wave crests that start tumbling. Dense streaks of foam in wind. Poor visibility from spray is possible. |
| 10 |
Tempesta
Storm
Tempête
Temporal | 24,5 - 28,4 |
48 - 55 |
Very high waves with long, curling crests (billows). Foam streaks tend to converge and sea surface appears white from blowing foam. Heavy tumbling of sea and poor visibility. |
| 11 |
Tempesta violenta
Violent storm
Violente tempête
Temporal duro, Borrasca | 28,5 - 32,6 |
56 - 63 |
Waves high enough to hide small and medium sized ships. Sea covered with patches of white foam. Edges of wave crests blown into froth and poor visibility. |
| 12 |
Uragano
Hurricane
Ouragan
Huracán | over 32,7 |
over 64 |
Sea white with spray and foam. Visibility almost non existent. |
|
Scale
The scale takes its name from admiral Francis Beaufort (1774-1857), hydrographer of the Royal Navy, who in 1805 proposed a method to classify the wind force into 13 degrees. In 1831 the scale was first used on the Beagle in the celebrated voyage and in 1838 it was officially adopted by British Admiralty and later by all other countries. |
