Beaufort's Scale

From wind chill factors to air speed indicators, all the ways in which we refer to moving air have to do with how fast it is going. Yet that wasn't always true. The first international standard dealing with wind paid no attention to miles per hour, meters per second, or even knots. Thanks to geography, northerners have a special claim on that early standard.

Captain Francis Beaufort wasn't on the 1826 British expedition that identified the sea to the north of Alaska and western Canada given his name. He was in England, working as a hydrographer in the Admiralty. Reference books such as Orth's Dictionary of Alaska Place Names note that Sir John Franklin, who led the expedition, named the sea "in honor of his friend" Beaufort--but Franklin may have been motivated by political prudence as well. Beaufort was a rising star in the Admiralty, where he eventually became known to history as Admiral Sir Francis Beaufort, the man who invented the scale of wind velocities.

Beaufort was a clever young commander in 1805, when he devised his scale. Like many technical advances, the scale was developed for military applications. Its earliest form gave thirteen steps, force 0 to force 12, for the effects of wind on a fully rigged man-of-war sailing vessel. Although the Royal Navy was most interested in wind effect on sails, moving air at the low end of the scale could barely be perceived in heavy canvas. Wind of force 1, for example, a light air, would barely bend smoke rising from the galley cookstove. At force 3, a gentle breeze, the flag would stir slightly. By force 6, a strong breeze, the wind would be whistling in the rigging and the sails would be bellied-out and drawing.

Not every ship in the Royal Navy was a man-of-war, so the scale was soon extrapolated to cover wind effects readable from the sea surface. In the calm of force 0, the sea is mirrorlike. By the fresh gale of force 8, long strings of foam appear on the ocean, and waves are 13 to 20 feet high.

The Beaufort scale provided an enormously useful standard for mariners. Captains knew what to expect when they ventured into waters "likely to experience offshore winds of force 7 from May to October," as the Admiralty could now tell them. An officer new to a ship perhaps could read in his predecessor's log notes that the vessel had survived true storms--winds of force 11, which means waves of 30 to 45 feet--and gain confidence in her seaworthiness. Moving at a steady pace, in 1838 the Royal Navy declared wind force on the Beaufort scale to be mandatory information for log entries in all British naval vessels.

Meteorologists moved even more slowly. It wasn't until 1874 that the International Meteorological Committee agreed on the appropriate phenomena on sea and land to delimit the thirteen wind strengths. Then the revised and expanded Beaufort scale became the official descriptive system for winds, to be used in international weather reports sent by telegraph.

But note that curious omission in the Beaufort scale: it did not deal with how fast the wind blew. It wasn't until 1926 that the International Meteorological Committee finally decided upon the proper wind speeds to match the names and numbers assigned to the wind effects Beaufort described more than a century before.

It's almost unthinkable now to conceive of a scientific system of measurement not based on the quantifiable, but in 1805 Francis Beaufort didn't care how fast the wind went. He was concerned with its effects, not its statistics. He did not have accurate anemometers, but he had a navy full of keen observers whose lives depended on their ability to judge wind and weather. What he gave them was a common language, one eventually to be shared by landlubbers, to describe and share their observations accurately.

Maps show the Beaufort Sea as a great bight of the Arctic Ocean extending from the eastern side of Point Barrow all the way to Banks Island at the edge of the Canadian Arctic Archipelago. It's still a place for practical people, those more concerned with what the weather can do to you rather than numbers on an anemometer or thermometer. Even if he never saw its shores, Beaufort's name is an appropriate one for our northern sea.