Force | Speed
Knots|Km/h | Name | Condition at Sea | Conditions on Land | |
0 | <1 | <2 | Calm | Sea like a mirror. | Smoke rises vertically. | |
1 | 1-3 | 1-5 | Light air | Ripples only | Smoke drifts and leaves rustle. | |
2 | 4-6 | 6-11 | Light breeze | Small wavelets(0.2m), Crests have a glassy appearance. | Wind felt on face. | |
3 | 7-10 | 12-19 | Gentle breeze | Large wavelets(0.6m), cests begin to break. | Flags extended, leaves move | |
4 | 11-16 | 20-29 | Moderate breeze | Small waves(1m), some whitecaps | Dust and small branches move. | |
5 | 17-21 | 30-39 | Fresh breeze | Moderatewave(1.8m), many whitecaps. | Small trees begin to sway. | |
6 | 22-27 | 40-50 | Strong breeze | Large waves(3m), probably some spray. | Large branches move, wires whistle, umbrellas are difficult to control. | |
7 | 28-33 | 51-61 | Near gale | Mounting sea(4m), with foam blown in streaks downwind | Whole trees in motion, inconvenience in walking. | |
8 | 34-40 | 62-74 | Gale | Moderately high waves(5.5m), crest break into spindrift | Difficult to walk against wind.Twigs and small branches blown off trees. | |
9 | 41-47 | 76-87 | Strong gale | High waves(7m), dense foam, visibility affected. | Minor structural damage may occur (shingles blown off roofs). | |
10 | 48-55 | 88-102 | Strom | Very high waves(9m), heavy sea roll, visibility inpaired. Surface generlly white. | Trees uprooted, structural damage likely. | |
11 | 56-63 | 103-118 | Violent storm | Exceotionally high waves(11m), visibility poor. | Widespread damage to structures. | |
12 | 64+ | 119+ | Hurricane | 14m waves, air filled with foam and spray, visibility bad. | Severe structural damage to buildings, widespread devastation. | |