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Beaufort
Force
Scale
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Rounded to even figures:
Wind (MPH)
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Original Beaufort Scale:
Wind (Knots)
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Nautical Terminology
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Appearance On Water
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Appearance On Land
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Notes
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0
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Less than 1.15
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Less than 1
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Calm
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Sea surface smooth and mirror-like
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Calm, smoke rises vertically
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Best for beginners.
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1
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Up to 3.5
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1-3
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Light Air
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Scaly ripples, no foam crests
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Smoke drift indicates wind direction, still wind vanes
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Easy for beginners.
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2
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Up to 7
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4-6
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Light Breeze
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Small wavelets, crests glassy, no breaking
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Wind felt on face, leaves rustle, vanes begin to move
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Easy for beginners.
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3
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8-11
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7-10
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Gentle Breeze
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Large wavelets, crests begin to break, scattered whitecaps
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Leaves and small twigs constantly moving, light flags
extended
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OK for beginners.
Suitable for sailing.
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4
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12-18
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11-16
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Moderate Breeze
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Small waves 1-4 ft. becoming longer, numerous whitecaps
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Dust, leaves, and loose paper lifted, small tree branches
move
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OK for intermediate paddlers.
Best for sailing.
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5
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19-24
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17-21
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Fresh Breeze
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Moderate waves 4-8 ft taking longer form, many whitecaps,
some spray
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Small trees in leaf begin to sway
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OK for advanced sailing.
Advanced paddlers only.
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6
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25-31
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22-27
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Strong Breeze
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Larger waves 8-13 ft, whitecaps common, more spray
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Larger tree branches moving, whistling in wires
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Small Craft Advisory is issued.
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7
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32-38
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28-33
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Near Gale
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Sea heaps up, waves 13-20 ft, white foam streaks off
breakers
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Whole trees moving, resistance felt walking against wind
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Paddlers should be off the water.
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8
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39-46
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34-40
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Gale
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Moderately high (13-20 ft) waves of greater length, edges of
crests begin to break into spindrift, foam blown in streaks
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Whole trees in motion, resistance felt walking against wind
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|
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9
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47-54
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41-47
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Strong Gale
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High waves (20 ft), sea begins to roll, dense streaks of
foam, spray may reduce visibility
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Slight structural damage occurs, slate blows off roofs
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10
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55-63
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48-55
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Storm
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Very high waves (20-30 ft) with overhanging crests, sea
white with densely blown foam, heavy rolling, lowered
visibility
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Seldom experienced on land, trees broken or uprooted,
"considerable structural damage"
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|
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11
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64-72
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56-63
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Violent Storm
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Exceptionally high (30-45 ft) waves, foam patches cover sea,
visibility more reduced
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|
|
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12
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73+
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64+
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Hurricane
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Air filled with foam, waves over 45 ft, sea completely white
with driving spray, visibility greatly reduced
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