Wind and Storm

      Very seldom in texts we use the term wind and here we would like to give some general information about the strength of wind and the consequences they leave on the nature and our surroundings. The data is also useful (almost indispensible) for sports such as windsurfing and skiing. A proper identification of wind strength gives us a real idea of what to expect when we go to the water for windsurfing or if we intend to go to a new peak. Our safe return depends on a proper preparation.

      The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort winds force scale, although it is a measure of wind speed and not of force in the scientific sense. The scale was devised in 1805 by Francis Beaufort (later Rear Admiral Sir Francis Beaufort), an Irish Royal Navy officer.

Effects Land / Sea

Still, calm air, smoke will rise vertically.

Water is mirror-like.

Rising smoke drifts,

wind vane is inactive.    

Small ripples appear on

water surface.

Leaves rustle, can feel 

wind on your face, wind vanes begin to move.

Small wavelets develop, crests are glassy.

 

Leaves and small twigs

move, light weight flags extend.       

Large wavelets, crests start

to break, some whitecaps.

 

Small branches move, raises dust, leaves and paper.

Small waves develop, becoming longer, whitecaps.

Small trees sway.

White crested wavelets (whitecaps) form, some spray.

Large tree branches move, telephone wires begin to "whistle", umbrellas are difficult to keep under control.

Larger waves form, whitecaps prevalent, spray.

Large trees sway,

becoming difficult to walk.         

Larger waves develop, white foam from breaking waves begins to be blown.

Twigs and small branches are broken from trees, walking is difficult.               Moderately large waves with blown foam.

Km/h

< 1

1-5

6-11

12-19

20-28

29-38

39-49

50-61

62-74

Wind speed

Knots

< 1

1-3

4-6

7-10

11-16

17-21

22-27

28-33

34-40

Mp/h

< 1

1-3

4-7

8-12

13-18

19-24

25-31

32-38

39-46

Beaufort

number of force

O

1

2

3

4

5

6

7

8

Wind and storm - Beaufort scale

Description

Calm

Light air

Light Breeze

Light Breeze

Moderate Breeze

Fresh Breeze

Strong Breeze

Moderate or Rear Gale

Gale or

Fresh Gale

Motivation for windsurfing