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The Beaufort Scale was originally developed in 1806 by Admiral Sir Francis Beaufort. The Beaufort Scale is divided into a series of speeds from 0 for calm winds to 12 for hurricanes. Each value represents a range of wind speeds with descriptions of effects on surface features

 
   
             
 

Beaufort

Number

 

Wind Speed

(mph)

Seaman's

Term

 

Effects on Land

 
  0   Under 1

Calm

Calm, smoke rises vertically.

 
  1   1 - 3

Light

Air

Smoke drift indicates wind direction, weather vanes do not move.

 
  2   4 - 7

Light

Breeze

Wind felt on face, leaves rustle, Vanes begin to move.

 
  3   8 -12

Gentle

Breeze

Leaves, small twigs in constant motion, small flags extended.

 
  4   13 -18

Moderate

Breeze

Dust, leaves and loose paper move up, small branches move.

 
  5   19 - 24

Fresh

Breeze

Small trees begin to sway.

 
  6   25 - 31

Strong

Breeze

Large branches of trees in motion.

 
  7   32 - 38

Moderate

Gale

Whole trees in motion, resistance felt in walking against wind.

 
  8   39 - 46

Fresh

Gale

Twigs and small branches broken off trees.

 
  9   47 - 54

Strong

Gale

Slight structural damage occurs, slates blown from roofs.

 
  10   55 - 63

Whole

Gale

Tress damaged, structural damage occurs

 
  11   64 - 72

Storm

Widespread damage

 
  12   72 or higher

Hurricane

Force

Violent destruction.

 
               

 

       
             
             
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