TBL 10-2-3 Table of Common References for Estimating Wind Velocity Wind (Knots) Wind Classification Appearance of Wind Effects On the Water Less than 1 1-3 Calm Light Air Sea surface smooth and mirror-like Scaly ripples, no foam crests 4-6 Light Breeze 7-10 Gentle Breeze 11-16 Moderate Breeze 17-21 Fresh Breeze 22-27 Strong Breeze 28-33 Near Gale 34-40 Gale 41-47 Strong Gale 48-55 Storm 56-63 Violent Storm Hurricane Small wavelets, crests glassy, no breaking Large wavelets, crests begin to break, scattered whitecaps Small waves 1-4 ft. becoming longer, numerous whitecaps Moderate waves 4-8 ft. taking longer form, many whitecaps, some spray Larger waves 8-13 ft., whitecaps common, more spray Sea heaps up, waves 13-20 ft., white foam streaks off breakers Moderately high (13-20 ft.) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks High waves (20 ft.), sea begins to roll, dense streaks of foam, spray may reduce visibility Very high waves (20-30 ft.) with overhanging crests, sea white with densely blown foam, heavy rolling, lowered visibility Exceptionally high (30-45 ft.) waves, foam patches cover sea, visibility more reduced Air filled with foam, waves over 45 ft., sea completely white with driving spray, visibility greatly reduced On Land Calm, smoke rises vertically Smoke drift indicates wind direction, wind vanes are still Wind felt on face, leaves rustle, vanes begin to move Leaves and small twigs constantly moving, light flags extended Dust, leaves, and loose paper lifted, small tree branches move Small trees in leaf begin to sway Larger tree branches moving, whistling in wires Whole trees moving, resistance felt walking against wind Whole trees in motion, resistance felt walking against wind Slight structural damage occurs, slate blows off roofs Seldom experienced on land, trees broken or uprooted, "considerable structural damage" EXAMPLE- Wind from the South-East, estimated speed 15 knots. Wind shifted from North-East about fifteen minutes ago, and is gusty. Special Operations 10-2-15