storm

Beaufort Scale

Wind is simply known as the movement of air in horizontal motion. Air moves due to different factor those are – 

  1. Horizontal pressure – gradient
  2. Rotation of the Earth(the coriolis force),
  3. Frictional forces,
  4. Centrifugal action of wind ,

Beaufort scale is used to measure the wind speed and it was discovered by Francis Beaufort in 1805.  

The following table represents the Beaufort scale number and wind speed and observable descriptions. 

Beaufort scale NumberKnots (unit of speed)Explanatory termsObservable description
0Less than 1CalmCalm smoke rises vertically
1 1-3Light airDirection of wind shown by smoke drift, but not by wind vanes
2 4-6Light breezeWinds felt on face, leaves rustle; ordinary vane moved by wind
3 7-10Gentle breezeLeaves and small twigs in constant motion wind extends light flag
411-16Moderate breezeRaises dust and loose paper; small branches are moved
517-21Fresh breezeSmall trees in leaf begin to sway; wavelets form on inland water
622-27Strong breezeLarge branches in motion , whistling heard in telegraph wires; umbrellas used with difficulty
728-33Moderate galeWhole trees in motion, inconvenience felt when walking against wind.
830-40Fresh galeBreaks twigs from trees , impedes progress generally
941-47Strong galeSlight structural damage occurs, chimneys and slates carried away
1048-55Whole gale Seldom experienced inland ,trees, uprooted, considerable structural damage done
1156-63StormVery rarely experienced ; accompanied by widespread damage
1264-71HurricaneViolence and destruction 
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