Beaufort Scales (Wind Speed)
Originally found here.
| Force | Speed knots | Speed km/h | Speed mi/h | Name | Conditions at Sea | Conditions on Land |
|---|---|---|---|---|---|---|
| 0 | < 1 | < 2 | < 1 | Calm | Sea like a mirror. | Smoke rises vertically. |
| 1 | 1-3 | 1-5 | 1-4 | Light air | Ripples only. | Smoke drifts and leaves rustle. |
| 2 | 4-6 | 6-11 | 5-7 | Light breeze | Small wavelets (0.2 m). Crests have a glassy appearance. | Wind felt on face. |
| 3 | 7-10 | 12-19 | 8-11 | Gentle breeze | Large wavelets (0.6 m), crests begin to break. | Flags extended, leaves move. |
| 4 | 11-16 | 20-29 | 12-18 | Moderate breeze | Small waves (1 m), some whitecaps. | Dust and small branches move. |
| 5 | 17-21 | 30-39 | 19-24 | Fresh breeze | Moderate waves (1.8 m), many whitecaps. | Small trees begin to sway. |
| 6 | 22-27 | 40-50 | 25-31 | Strong breeze | Large waves (3 m), probably some spray. | Large branches move, wires whistle, umbrellas are difficult to control. |
| 7 | 28-33 | 51-61 | 32-38 | Near gale | Mounting sea (4 m) with foam blown in streaks downwind. | Whole trees in motion, inconvenience in walking. |
| 8 | 34-40 | 62-74 | 39-46 | Gale | Moderately high waves (5.5 m), crests break into spindrift. | Difficult to walk against the wind. Twigs and small branches blown off trees. |
| 9 | 41-47 | 76-87 | 47-54 | Strong gale | High waves (7 m), dense foam, visibility affected. | Minor structural damage may occur (shingles blown off roofs). |
| 10 | 48-55 | 88-102 | 55-63 | Storm | Very high waves (9 m), heavy sea roll, visibility impaired. Surface generally white. | Trees uprooted, structural damage likely. |
| 11 | 56-63 | 103-118 | 64-73 | Violent storm | Exceptionally high waves (11 m), visibility poor. | Widespread damage to structures. |
| 12 | 64+ | 119+ | 74+ | Hurricane | 4 m waves, air filled with foam and spray, visibility bad. | Severe structural damage to buildings, widespread devastation. |