The Beaufort Scale of Wind Force was developed in 1805 by Admiral Sir Francis Beaufort as a means for sailors to gauge wind speeds through visual observations of the sea state.
The scale runs from Force 0 (calm) to Force 12 (Hurricane).
|Force||Wind (Knots)||Classification||Wind Effect|
|0||<1||Calm||Sea surface smooth and mirror-like.|
|1||1-3||Calm||Scaly ripples, no foam crests.|
|2||4-6||Light Breeze||Small wavelets, crests glassy, no breaking.|
|3||7-10||Gentle Breeze||Large wavelets, crests begin to break, scattered whitecaps.|
|4||11-16||Moderate Breeze||Small waves 1-4 ft. becoming longer, numerous whitecaps.|
|5||17-21||Fresh Breeze||Moderate waves 4-8 ft taking longer form, many whitecaps, some spray.|
|6||22-27||Strong Breeze||Larger waves 8-13 ft, whitecaps common, more spray.|
|7||28-33||Near Gale||Sea heaps up, waves 13-20 ft, white foam streaks off breakers.|
|8||34-40||Gale||Moderately high (13-20 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks.|
|9||41-47||Strong Gale||High waves (20 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility.|
|10||48-55||Storm||Very high waves (20-30 ft) with overhanging crests, sea white with densely blown foam, heavy rolling, lowered visibility.|
|11||56-63||Violent Storm||Exceptionally high (30-45 ft) waves, foam patches cover sea, visibility more reduced.|
|12||64+||Hurricane||Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced.|
This is the scale that we use in our book busy doing nothing.