Windswept_ The Story of Wind and Weather - Marq de Villiers [65]
Since the Royal Navy was involved, it made sense that their Beaufort numbers were incorporated into the new weather office data. But there were obvious problems—the new weathermen in Boston or Belfast or Bratislava, many of whom had never seen the sea, never mind a man-of-war, had trouble agreeing with each other on definitions. The result was confusion, made worse by the proliferation of wind scales. By 1900 there were more than thirty sets in vogue, some disagreeing by more than 100 percent. "It was no longer clear just what the old force scale meant, and few men survived who were competent to judge what the behavior of an 1805 man-of-war would be."14
The first solution was to produce a landlubber's version of Beaufort's observations, in which his "light air giving steerage way" was changed to "light air, direction shown by smoke but not by wind vanes," and his hurricane was changed from "that which no canvas can withstand" to the more stark "devastation occurs."
But in the end this wouldn't do either. In 1912 the International Commission for Weather Telegraphy began the search for real wind speed numbers to attach to the Beaufort observations. A set of equivalents was accepted internationally in 1926, and revised in 1946. By 1955, wind velocities in knots replaced Beaufort numbers on weather maps. At the same time, a gust was defined as "any wind speed of at least 16 knots that involves a change in wind velocity with a difference between peak and lull of at least 10 knots lasting for less than 20 seconds." A squall is more intense, "having a wind speed of at least 16 knots that is sustained at 22 knots or more for at least 2 minutes (in the U.S.) or one minute (everywhere else)."
And so we arrive at the modern Beaufort wind scale, which ranges from dead calm through light air (1 to 3 knots), to hurricane, measured at "greater than 64 knots" (74 miles an hour).
This was much more useful, and usable. Still, modern sailors often use Beaufort's own ship-oriented point of view. As Scott Huler put it in his book Defining the Wind, "Sailors tend to define the Beaufort scale by simply looking at the sea—how high the waves are, what the surface looks like. As for the higher numbers—10, u or 12—who cares? It's just surviving anyway."15 The fishermen on the eastern seaboard tend not to use a scale at all. They judge the wind by the swell and the break of the sea and by the sound of the wind in the rigging, and know from the pitch of the boat and the pitch of the sound when it is time to head for home. Even I have learned to judge a Force 9 gale ("41 to 47 knots") by the sound the spruces make in the wind.
If it is useful to know the speed, and therefore the effects, of gales and storms, how much more useful to have a measure of the planet's most powerful natural force, the Atlantic hurricane and Pacific typhoon? Curiously, though hurricanes were known in the Caribbean from the beginning of the exploration era, and though destructive hurricanes had battered the American coast for centuries (the 1900 hurricane that slammed into Texas all but destroyed Galveston), and though some of these storms actually made their way up the continent as far as the Great Lakes and occasionally back across the Atlantic to Europe, it wasn't until 1973 that a scale could be agreed on.
In the end, it was the construction industry and not the meteorologists that pressed for a solution, and the scale that was finally adopted was devised by Herbert Saffir, a building engineer, and Robert Simpson of the National Hurricane Center, which had been established in Miami. So the scale is called the Saffir-Simpson hurricane scale. It is a 1 to 5 rating based