Wind force at the earth's surface according to the Beaufort scale (at a standard
height of 10 m above an open flat surface) |
| Beaufort points
| Verbal definition of wind force
| Wind speed, m/sec
| Effect of wind |
| on land
| at sea |
| 0
| Calm
| 0-0,2
| Calm. Smoke rises vertically
| Mirror-like smooth sea |
| 1
| Light
| 0,3-1,5
| Wind direction noticeable by smoke drift, but not by the weather vane
| Ripples, no foam on the crests |
| 2
| Gentle
| 1,6-3,3
| Wind movement felt on the face, rustles leaves, sets
the weather vane in motion
| Short waves, crests do not break and appear
glass-like |
| 3
| Moderate
| 3,4-5,4
| Leaves and thin branches of trees constantly sway, wind
unfurls upper flags
| Short, well-defined waves. Crests, when breaking,
form glass-like foam, occasionally forming small white horses |
| 4
| Fresh
| 5,5-7,9
| Wind raises dust and paper, sets thin
tree branches in motion
| Waves elongated, white horses visible in many places |
| 5
| Strong
| 8,0-10,7
| Thin tree trunks sway, waves with crests appear on the water
crests
| Well-developed in length, but not very large waves, everywhere
visible white horses (in some cases, spray forms) |
| 6
| Very Strong
| 10,8-13,8
| Thick tree branches sway, telegraph wires hum
| Large waves begin to form. White foamy crests
occupy significant areas (sprays are likely) |
| 7
| Whole Gale
| 13,9-17,1
| Tree trunks sway, walking against the wind is difficult
| Waves pile up, crests break, foam lies in streaks across
the wind |
| 8
| Storm
| 17,2-20,7
| Wind breaks tree branches, walking against the wind is very difficult
| Moderately high long waves. Spray begins to
fly off the crests. Foam strips lie in rows along the wind direction |
| 9
| Severe Gale
| 20,8-24,4
| Minor damage; wind tears off smoke caps and
roof tiles
| High waves. Foam lies in wide dense strips along
the wind. Wave crests begin to break and scatter in spray, which
reduces visibility |
| 10
| Violent Storm
| 24,5-28,4
| Significant building damage, trees uprooted.
Rarely seen on land
| Very high waves with long downward bending crests.
Forming foam is blown by the wind into large flakes in the form of thick white strips.
The sea surface is white with foam. The loud crash of waves is similar to blows. Visibility
poor |
| 11
| Hurricane
| 28,5-32,6
| Extensive destruction over a large area. Very
rarely observed on land
| Exceptionally high waves. Small and medium-sized ships sometimes
disappear from view. The sea is all covered with long white flakes of foam,
arranged along the wind. Wave edges are blown into foam everywhere. Visibility is poor
|
| 12
| Hurricane
| 32.7 and more
|
| The air is filled with foam and spray. The sea is all covered with foam
foam. Very poor visibility |
