Beaufort scale

The Beaufort scale is a system for describing wind speed based on observed sea conditions. The scale consists of thirteen forces, ranging from force 0 (calm) to force 12 (hurricane).

It is the standard way to describe wind speed at sea and is used in most nautical weather forecasts.

The Beaufort scale is named after Francis Beaufort, who devised the system in 1805 and later became head of the Hydrographic Office of the British Admiralty.

The original scale defined each force in terms of the effect of the wind on the sails of a man of war. In 1906, with the growth of steam power, the descriptions were changed to describe the state of the sea rather than the sails of a man of war, and at the same time land-based definitions were created.