knots mi h-1 m s-1 km h-1 Seaman's term World Meteoro-
Effects observed on land 0 <<1 <<1 0,0-0,2 <<1 Calm Calm Sea like mirror. Calm; smoke rises vertically. 1 1-3 1-3 0,3-1,5 1-5 Light air Light air Ripples with appearance of scales; no foam crests. Smoke drift indicates wind direction; vanes do not move. 2 4-7 4-7 1,6-3,3 6-11 Light breeze Light breeze Small wavelets; crests of glassy appearance, not braking. Wind felt on face; leaves rustle; vanes begin to move. 3 7-10 8-12 3,4-5,4 12-19 Gentle breeze Gentle breeze Large wavelets; crests begin to brake; scattered whitecaps. Leaves, small twigs in constant motion; light flags extended. 4 11-16 13-18 5,5-7,9 20-28 Moderate breeze Moderate breeze Small waves, becoming longer; numerous whitecaps. Dust, leaves, and loose paper raised up; small branches move. 5 17-21 19-24 8,0-10,7 29-38 Fresh breeze Fresh breeze Moderate waves, taking longer form; many whitecaps; some spray. Small trees in leaf begin to sway. 6 22-27 25-31 10,8-13,8 39-49 Strong breeze Strong breeze Larger waves forming; whitecaps everywhere; more spray. Larger branches of trees in motion; whistling heard in wires. 7 28-33 32-38 13,9-17,1 50-61 Moderate gale Near gale Sea heaps up; white foam from breaking waves begins to be blown in streaks. Whole trees in motion; resistance felt in walking against wind. 8 34-40 39-46 17,2-20,7 62-74 Fresh gale Gale Moderately high waves of greater length;edges of crests begin to break into spindrift; foam is blown in well marked streaks. Twigs and small branches broken off trees; progress generally impeded.