Estimating Wind Speed ===================================================================== Michael Sawyer Feb 1994 According to Chapman's piloting, the ranges (and descriptions) given are verbatim that of the beauford scale. It may be worthwhile to include the rest of the scale in the table (esp. for those of us who are lucky enough to fly next to water). Note that the descriptions of sailboats are probably the best indicator; a sailboat will show the winds up high as well as the surface winds. At Sea descriptions given are really only for measuring out at sea, but, since whitecapping and spray are local events, that part of the description should be reasonably accurate. Force # = Beauford scale force number WMO Desc = World Meteorological Organization Description [The following from Chapman Piloting, 60/ed, 1991, Hearst Corp., except Kiters: comments] Force Speed: WMO #: mph: km/hr: Desc: Effects Described: 0 <1 <1 Calm Sea: Like a mirror Near Land: Calm On Land: Calm; Smoke rises vertically Kiters: Grrrr... 1 1-3 1-5 Light Air Sea: (1-3 kn) Ripples with appearance of scales; no foam crests Near Land: Small sailboat just has steerage way On Land: Smoke drift indicates wind direction; vanes do not move 2 4-7 6-11 Light Sea: (4-6 kn) Small wavelets; crests of glassy Breeze appearance, not breaking Near Land: Winds fill the sails of small boats which then travel at 1 - 2 knots On Land: Wind felt on face; leaves rustle; vanes begin to move 3 8-12 12-19 Gentle Sea: (7-10 kn) Large wavelets; crests begin to break, Breeze scattered whitecaps Near Land: Sailboats begin to heel and travel at about 3-4 knots On Land: Leaves, small twigs in constant motion; light flags extended 4 13-18 20-28 Moderate Sea: (11-16 kn) Small waves 0.5 - 1.25 meters high, Breeze becoming longer; numerous whitecaps Near Land: Good working breeze, sailboats carry all sails with good heel On Land: Dust, leaves, and loose paper raised up; small branches move 5 19-24 20-38 Fresh Sea: (17-21 kn) Moderate waves of 1.25 - 2.5 m Breeze taking longer form; many whitecaps; some spray Near Land: Sailboarts shorten sail On Land: Small trees in leaf begin to sway Kiters: Probably too much wind for most people 6 25-31 39-49 Strong Sea: (22-27 kn) Larger waves 2.5 - 4 meters forming; Breeze whitecaps everywhere, more spray Near Land: Sailboats have double-reefed mailsails On Land: Larger branches of trees in motion; whistling heard in wires Kiters: Not for the weak of heart. 7 32-38 50-61 Near Sea: (28-33 kn) Sea heaps up, waves 4 - 6 m; Gale white foam from breaking waves begins to be blown in streaks Near Land: Boats remain in harbor; those at sea heave-to On Land: Whole trees in motion; resistance felt in walking against wind 8 39-46 64-72 Gale Sea: (34-40 kn) Moderately high (4 - 6 m) waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks Near Land: All boats make for harbor, if near On Land: Twigs and small branches broken off trees; progress generally impaired Kiters: Probably shouldn't be out 9 47-54 75-88 Strong Sea: (41-47 kn) High waves (6 m); sea begins Gale to roll; dense streaks of foam; spray may reduce visibility On Land: Slight structural damage occurs; slate blown from roofs Kiters: Get off the beach and take cover. 10 55-63 89-102 Storm Sea: (48-55 kn) Very high waves (6 - 9 m) with overhanging crests; sea takes a white appearance as foam is blown in very dense streaks; rolling is heavy and visibility is reduced On Land: Seldom experienced on land; Trees broken or uprooted; considerable damage occurs 11 64-72 103-117 Violent Sea: (56-63 kn) Exceptionally high (9-14 m) waves; Storm sea covered with white foam patches; visibility still more reduced On Land: Very rarely experienced on land; usually accompanied by widespread damage 12 73+ 118+ Hurricane Sea: (64+ kn) Air filled with foam; waves over 14 meters; sea completly white with driving spray; visibility greatly reduced Kiters: Perfect time to try out that new stack of Flexi's. :>