In 1805 Rear Admiral, Sir Francis Beaufort devised a method of describing the force of a wind with a relatively simple numbering system that indicated its various strengths.

The scale was modified in 1926 and relates to the estimated velocity and effects of the wind at around 10m above ground level.

Sir Francis' original scale was designed to determine wind force at sea and its effect on a Royal Navy ship.

He classified a force 2 wind as "that in which a well conditioned man-o-war, with all sail set and clean full, would go in smooth water from one to two knots." A force 12 wind was, "That which no canvas could withstand."

Calm

Smoke rises straight up.

Light Air

Wind direction is shown by the drift of smoke.

Slight Breeze

You will feel the wind on your face and see leaves and twigs move. The wind vane moves.

Gentle Breeze

Leaves and twigs constantly move around and some smaller flags stand straight out.

Mod. Breeze

Dust, papers and plastic shopping bags blow about and small branches sway.

Fresh Breeze

Small trees sway and waves form on rivers and lakes.

Strong Breeze

Large branches sway and it is hard to control your umbrella, but isn't it always?

Moderate Gale

Trees sway and it is difficult to walk against the wind.

Fresh Gale

Twigs break off trees and walking is very difficult.

Strong Gale

There is slight building damage, roof sheeting, light tiles and shingles rattle and can blow off.

Whole Gale

Considerable building damage and large trees are uprooted.

Storm

Widespread major damage and our S.E.S. is called in to assist.

Hurricane/TC

Violent destruction.