Beaufort scale

The Beaufort scale ( BOH-fərt) is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale. It was devised in 1805 by Francis Beaufort, a hydrographer in the British Royal Navy. It was officially adopted by the Royal Navy and later spread internationally.

History

The scale that carries Beaufort's name had a long and complex evolution from the previous work of others (including Daniel Defoe the century before). In the 18th century, naval officers made regular weather observations, but there was no standard scale and so they could be very subjective — one man's "stiff breeze" might be another's "soft breeze"—: Beaufort succeeded in standardising a scale. The scale was devised in 1805 by Francis Beaufort (later Rear Admiral), a hydrographer and a Royal Navy officer, while serving on HMS Woolwich, and refined until he was Hydrographer of the Navy in the 1830s, when it was adopted officially. It was first used during the 1831–1836 "Darwin voyage" of HMS Beagle under Captain Robert FitzRoy, who was later to set up the first Meteorological Office in Britain giving regular weather forecasts.

The initial scale of 13 classes (zero to 12) did not reference wind speed numbers, but related qualitative wind conditions to effects on the sails of a frigate, then the main ship of the Royal Navy, from "just sufficient to give steerage" to "that which no canvas sails could withstand".

The scale was made a standard for ship's log entries on Royal Navy vessels in the late 1830s and, in 1853, the Beaufort scale was accepted as generally applicable at the First International Meteorological Conference in Brussels.