BEAUFORT SCALE
Beaufort

Speed

Sea State On Land
Force Description knots km/h mph
0 Calm Less than 1 Less than 1 Less than 1 Sea like a mirror Smoke rises vertically.
1 Very Light 1-3 1-5 1-3 Ripples with appearance of scales, no form crests Direction of wind shown by smoke drift but not by wind vanes.
2 Light breeze 4-6 6-11 4-7 Wavelets, small but pronounced. Crests with glassy appearance, but do not break. Wind felt on face , leaves rustle, ordinaryt wind vane moved by wind.
3 Gentle breeze 7-10 12-19 8-12 Large wavelets, crests begin to break. Glassy looking foam, occasional white horses. Leaves and small twigs in constant motion, wind extends white flag.
4 Moderate breeze 11-16 20 - 29 13 - 18 Small waves becoming longer, frequent white horses. Wind raises dust and loose paper, small branches move.
5 Fresh breeze 17 - 21 30 - 39 19 - 24 Moderate waves of pronounced long form. Many whit horses, some spray. Small trees in leaf start to sway, crested wavelets on inland waters.
6 Strong breeze 22 - 27 40 - 50 25 - 31 Some large waves, extensive white foam crests, some spray. Large branches in motion, whistling in telegraph wires, umberellas used with difficulty.
7 Near gale 28 - 33 51 - 61 32 - 38 Sea heaped up, white foam from breaking waves blowing in streaks with the wind. Whole trees in motion, inconvient to walk against wind.
8 Gale 34 - 40 62 - 74 39 - 46 Moderately high and long waves. Crests break into spin drift, blowing foam in well marked streaks. Twigs break from trees, difficult to walk.
9 Strong gale 41 - 47 75 - 87 47 - 54 High waves, dense foam streaks in wind, wave crests topple, tumble and roll over. Spray reduces visability. Slight structural damage occuers, chimney pots and slates removed.
10 Storm 48 - 55 88 - 101 55 - 63 Very high waves with long overhanging crests. Dence blowing foam, sea surface appears white. Heavy tumbling of sea, shock-like, poor visability. Trees uprooted, considerable structural damage occurs.
11 Violent storm 56 - 63 102 - 117 64 - 73 Exceptionally high waves, sometimes concealing small and medium sized ships. Sea comletely covered with long white patches of foam. Edges of wave crests blown into froth . Poor visability. Widespread damage.
12 Hurricane >64 >119 >74 Air filled with foam and spray, sea white with driving spray, visability. Widespread damage.

Wikipedia: Beaufort Scale

Questions, comments or suggestions.  Email jnull@ggweather.com
Copyright 2015,
Golden Gate Weather Services
Reproduction in full or part is prohibited without
permission.