Antroposi — the Beaufort wind force scale | antroposi.org
From Beaufort's frigate-sail classes on HMS Woolwich through Royal Navy adoption, the 1853 Brussels conference, the 1916 sea-state rewrite and the 1923 anemometer standardisation.
The scale was devised in 1805 by Francis Beaufort, a hydrographer and Royal Navy officer, while serving on HMS Woolwich. The initial scale of 13 classes, zero to 12, did not reference wind speed numbers; it related qualitative wind conditions to effects on the sails of a frigate, from 'just sufficient to give steerage' to 'that which no canvas sails could withstand'. Wind speed was not part of the original design at all.
In the late 1830s the scale was made a standard for ship's log entries on Royal Navy vessels, giving the fleet a shared vocabulary for reporting weather. In 1853 it was accepted as generally applicable at the First International Meteorological Conference in Brussels, moving the scale from a navy convention to an international one.
Two later revisions changed what the scale measured. In 1916 the descriptions were changed to how the sea, not the sails, behaved and extended to land observations, so the scale could be used away from a sailing ship. In 1923 anemometer rotations were standardised to scale numbers under George Simpson of the UK Meteorological Office, which finally attached instrument readings to the force numbers.
On narrow screens, swipe or scroll the plate sideways.
The empirical wind-speed relation v = 0.836 × B^1.5 m/s belongs to this instrumented phase: it converts the integer force number into a speed at 10 metres above the sea surface, with the knot form v = 1.625 × B^1.5 for marine use.
Each step widened the audience. Sailors' logs, then international meteorology, then land observers and instrument readings, all sharing the same 0–12 numbering.
The history explains why the scale reads the way it does today: observation first, numbers second, with the sea-state and land-effect columns carrying the meaning and the formula carrying the arithmetic.
Further reading