Beaufort Wind Force

Wind speed in:

Description Term

Sea Criterion

State of Sea

kts

m/s

Scale

Description

Height

0

< 1

0–0,2

Calm

              Sea likes a mirror.

0

Calm (glassy)

0

1

1–3

0,3–1,5

Light air

              Ripples with the appearance of scales are formed, but without foam crests.

1

Calm (rippled)

0–0,1

2

4–6

1,6–3,3

Light breeze

              Small wavelets, still short but more pronounced, crests have a glassy appearance and do not break.

2

Smooth (vaveletes)

0,1–0,5

3

7–10

3,4–5,4

Gentle breeze

              Large wavelets. Crests begin to break. Foam of glassy appearance. Perhaps scattered with horses

3

Slight

0,5–1,25

4

11–16

5,5–7,9

Moderate breeze

              Small waves, becoming longer; fairly frequent with horses.

4

Moderate

1,25–2,5

5

17–21

8,0–10,7

Fresh breeze

              Moderate waves, taking a more pronounced long form; many white horses are formed.

(Chance of some spry)

5

Rough

2,5–4

6

22–27

10,8–13,8

Strong breeze

              Large waves begin to form; the white foam crest are more extensive everywhere.

(Probably some spry)

7

28–33

13,9–17,1

Near gale

              Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind.

6

Very rough

4–6

8

34–40

17,2–20,7

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.

7

High

6–9

9

41–47

20,8–24,4

Strong gale

              High waves. Dense streaks of foam along the direction of the wind. Crests of waves begin to topple, tumble and roll over. Spry may affect visibility.

10

48–55

24,5–28,4