This scale was developed in 1805 by British Rear-Admiral Sir Francis Beaufort as a standard for estimating wind speed, not with instrumentation, but by using your own senses and observing the wind's effects on your surroundings. The scale is still used today by mariners and more recently kite fliers. Most kite manufacturers use the Beaufort Scale to list the suitable wind ranges for their products.
Bft. Force | Knots | Mph. | Kph | Meters/Sec. | Classification | Appearance on Land | Appearance on Water | For the Power Kite Flier |
---|---|---|---|---|---|---|---|---|
0 | < 1 | < 1.15 | <1.83 | < 0.51 | Calm | Calm, smoke rises vertically | Sea surface smooth and mirror-like. | Relax, hang out, inspect your kite, wait for wind. |
1 | 1 - 3 | 1.1 - 3.5 | 2 - 5.5 | 0.5 - 1.5 | Light Air | Smoke drift indicates wind direction. Wind vanes are still. | Scaly ripples, no foam crests. | 7 meter kites might fly, but usually only veterans have these. Novices with smaller kites will have to wait for more. |
2 | 4 - 6 | 4.6 - 7 | 7.5 - 11 | 2 - 3 | Light Breeze | Wind Felt on face, leaves rustle, wind vanes begin to move. | Small wavelets, crests glassy,no breaking. | 5 meter and larger can come out of the bag. Beginners should be wary of gusts, if flying the big ones. |
3 | 7 -10 | 8 - 11.5 | 13 - 18.5 | 3.5 - 5 | Gentle Breeze | Leaves and small twigs constantly moving, light flags moving. | Large wavelets, crest begin to break, scattered whitecaps ("sheep in the pasture"). | Novices with smaller kites up to 3-4m can have safe fun. Veterans with bigger kites are feeling the pull and starting to smile. |
4 | 11 - 16 | 12.5 - 18.5 | 20 - 29 | 5.5 - 8 | Moderate Breeze | Dust, leaves and loose paper lifted, small tree branches move. | Small waves 1 -4 ft. becoming longer, numerous whitecaps. | Mid-sized kites (2.5-3.5m) are waking up and starting to pull hard. Beginners can have a blast with even 1.5m kites. |
5 | 17 - 21 | 19.5 - 24 | 31 - 38.5 | 9 - 11 | Fresh Breeze | Small trees with leaves begin to sway. | Moderate waves, 4-8 ft. taking longer from, many whitecaps, some spray. | Big kites are all put away and mid-sized are in the hands of experts only. Novices without smaller kites should pack up. |
6 | 22 - 27 | 25 - 31 | 40.5 - 49.5 | 11.5 - 14 | Strong Breeze | Larger tree branches moving, whistling in wires. | Larger waves, 8-13 ft., whitecaps common, more spray | Experts with the right gear are either grinning or scared. Others have quit or been blown away. |
7 | 28 - 33 | 32 - 37 | 51 - 60.5 | 14.5 - 17 | Near Gale | Whole trees moving, resistance to walking against wind. | Sea heaps up 13 - 20 ft., white foam streaks off breakers. | The craziest veterans are down to their smallest kites. Others have wisely packed up. |
8 | 34 - 40 | 39 - 46 | 62 - 73 | 17.5 - 20.5 | Gale | Whole trees in motion, resistance to walking against wind. | Moderately high (13-20 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks. | Everybody is inside. No one wants to get hurt today. |
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