The Beaufort Wind Force Scale

Rear-Admiral Sir Francis Beaufort was born in Ireland in 1774. He entered the Royal Navy at the age of 13 and was a midshipman aboard the Aquilon. By 1800, he had risen to the rank of Commander. In the summer of 1805, Beaufort was appointed to the command of the Woolwich, a 44-gun man-of-war.

In 1806, he wrote in his log book a wind force scale. The scale was simple and very similar to one that Alexander Dalrymple had written in a book in 1789. A year later, he added some criteria to the 0-12 scale that indicated how much of a ship's sails would be employed by a British man-of-war under each condition. It was not describing the speed of the wind, but rather the effect of the wind on the ship's sails.

Over the following years, he continued to use his scale in his logs. It was finally adopted in December 1838 by the British Admiralty for use in all Royal Navy logbooks. "However, as ship design changed and steam power became widespread, the scale had to be modified.

In 1912, the International Commission for Weather Telegraphy sought some agreement on velocity equivalents for the Beaufort scale. A uniform set of equivalents was accepted in 1926 and revised slightly in 1946, extending the scale to 17 values (the added five values further refining the hurricane-force winds). By 1955, wind velocities in knots replaced Beaufort numbers on weather maps.

Modern Beaufort Scale, including the observed land conditions: