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Beaufort Scale

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One of the first scales to estimate wind speeds and the effects was created by Britain's Admiral Sir Francis Beaufort (1774-1857). He developed the scale in 1805 to help sailors estimate the winds via visual observations. The scale starts with 0 and goes to a force of 12. The Beaufort scale is still used today to estimate wind strengths.

 

FORCE SPEED MPH SPEED KNOTS DESCRIPTION SPECIFICATIONS FOR USE ON LAND IMAGE AT IBRSC
0 0-1 0-1 Calm Calm; smoke rises vertically. Beaufort Scale Force 0 Sailors stand around drinking tea.
1 1-3 1-3 Light Air Direction of wind shown by smoke drift, but not by wind vanes. Beaufort Scale Force 1 Very light and patchy: a Solo wins the race!
2 4-7 4-6 Light Breeze Wind felt on face; leaves rustle; ordinary vanes moved by wind. Beaufort Scale Force 2 A nice gentle racing wind. 
3 8-12 7-10 Gentle Breeze Leaves and small twigs in constant motion; wind extends light flag. Beaufort Scale Force 3  A decent racing breeze: things are getting lively.
4 13-18 11-16 Moderate Breeze Raises dust and loose paper; small branches are moved.  Beaufort Scale Force 4 Very lively, some capsizes. 
5 19-24 17-21 Fresh Breeze Small trees in leaf begin to sway; crested wavelets form on inland waters.  Beaufort Scale Force 5 Probably too much wind for novices unless using reefed Toppers. Much capsizing. 
6  25-31 22-27 Strong Breeze Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty.  beaufort scale force 6  Many sailors stay ashore and watch the fun
7  32-38 28-33  Near Gale Whole trees in motion; direction of wind shown by smoke drift, but not by wind vanes.  beaufort scale force 7 Only a few Lasers go out sailing 
8  39-46 34-40 Gale Breaks twigs off trees; generally impedes progress.  beaufort scale force 8 Only for the very experienced and foolhardy, and they soon regret it.
9  47-54 41-47 Severe Gale Slight structural damage occurs (chimney-pots and slates removed).  beaufort scaleforce 9 Sailors go and check that their boats and those next to them are well tied down. 
10  55-63 48-55 Storm Seldom experienced inland; trees uprooted; considerable structural damage occurs.  beaufort scale force 10 Sailors stay at home 
11  64-72 56-63 Violent Storm Very rarely experienced; accompanied by wide-spread damage.  beaufort scale force 11 Club Committee organise emergency meeting to discuss new clubhouse roof. Boats blown over fences, rescue boats blown ashore.
12  73-83 64-71 Hurricane    beaufort scale force 12  Michael Fish was right: fortunately we don't get these in the UK.

Images courtesy of Howtoons