|
| Force |
Wind
(Knots) |
WMO
Classification |
Appearance of Wind Effects |
| On the Water |
On Land |
| 0 |
Less than 1 |
Calm |
Sea surface smooth and mirror-like |
Calm, smoke rises vertically |
| 1 |
1-3 |
Light Air |
Scaly ripples, no foam crests |
Smoke drift indicates wind direction, still wind vanes |
| 2 |
4-6 |
Light Breeze |
Small wavelets, crests glassy, no breaking |
Wind felt on face, leaves rustle, vanes begin to move |
| 3 |
7-10 |
Gentle Breeze |
Large wavelets, crests begin to break, scattered whitecaps |
Leaves and small twigs constantly moving, light flags extended |
| 4 |
11-16 |
Moderate Breeze |
Small waves 1-4 ft. becoming longer, numerous whitecaps |
Dust, leaves, and loose paper lifted, small tree branches move |
| 5 |
17-21 |
Fresh Breeze |
Moderate waves 4-8 ft taking longer form, many whitecaps, some spray |
Small trees in leaf begin to sway |
| 6 |
22-27 |
Strong Breeze |
Larger waves 8-13 ft, whitecaps common, more spray |
Larger tree branches moving, whistling in wires |
| 7 |
28-33 |
Near Gale |
Sea heaps up, waves 13-20 ft, white foam streaks off breakers |
Whole trees moving, resistance felt walking against wind |
| 8 |
34-40 |
Gale |
Moderately high (13-20 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks |
Whole trees in motion, resistance felt walking against wind |
| 9 |
41-47 |
Strong Gale |
High waves (20 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility |
Slight structural damage occurs, slate blows off roofs |
| 10 |
48-55 |
Storm |
Very high waves (20-30 ft) with overhanging crests, sea white with densely blown foam, heavy rolling, lowered visibility |
Seldom experienced on land, trees broken or uprooted, "considerable structural damage" |
| 11 |
56-63 |
Violent Storm |
Exceptionally high (30-45 ft) waves, foam patches cover sea, visibility more reduced |
|
| 12 |
64+ |
Hurricane |
Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced |
|
Just another description
|
Beaufort
Number |
Wind
(knots) |
Desriptive
Term |
Land Observations |
Sea Observations |
| 0 |
<1 |
Calm |
Calm, smoke rises vertically |
Water calm, mirrorlike (.25 ft. waves) |
| 1 |
1-3 |
Light air |
Wind direction shown by smoke but not by windvanes |
Ripples with the appearance of scales (.5 to 1 ft. waves) |
| 2 |
4-6 |
Light breeze |
Leaves rustle; wind felt on face; windvanes moved by wind |
Small wavelets on water; crests have a glassy appearance and do not break.
2-3 ft. |
| 3 |
7-10 |
Gentle breeze |
Leaves and twigs in constant motion; wind extends light flag |
Large wavelets; crests begin to break; maybe scattered whitecaps. 3.5 to 5 ft. |
| 4 |
11-16 |
Moderate breeze |
Wind raises dust and loose paper; small branches move |
Moderate waves; fairly frequent whitecaps 6 to 8 ft. |
| 5 |
17-21 |
Fresh breeze |
Small leafed trees begin to sway |
Moderate, longer waves; many whitecaps; chance of spray. 9.5 to 13 ft. |
| 6 |
22-27 |
Strong breeze |
Large branches in motion; phone lines whistle |
Large waves form; white foam crests everywhere; probable spray. 13.5 to 19 ft. |
| 7 |
28-33 |
Moderate gale |
Whole trees in motion; difficult to walk against wind |
Sea heaps up; white foam starts to blow in streaks. 18 to 25 ft. |
| 8 |
34-40 |
Fresh gale |
Wind breaks twigs off trees; walking impeded |
Moderately high waves with crests beginning to break into foam that's blown in white streaks.
23 to 32 ft. |
| 9 |
41-47 |
Strong gale |
Slight damage to buildings occurs; shingles torn off roofs |
High waves; rolling seas; dense streaks of foam; wave crests begin to topple, tumble and
fall over. 29-41 ft. |
| 10 |
48-55 |
Whole gale |
Trees uprooted; considerable structural damage to buildings |
High waves with overhanging crests; sea is white. 64-72 ft. |
| 11-17 |
56+ |
Storm, Hurricane |
Widespread damage |
Huge waves; air filled with spray; little visibility
73 ft. + |
|
