British seaman set the standard for hurricanes

Scales: Before categories 1 through 5, Sir Francis Beaufort defined wind speeds and changed the way storms were forecast.

Medicine & Science

September 20, 2004|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

It's hard to remember a hurricane season when the public has been made more acutely aware of the Saffir-Simpson Hurricane Scale - normally an obscure measure of a tropical cyclone's destructive power.

When Hurricane Charley crept up on southwest Florida on Aug. 12, it had top winds of 85 mph. Forecasters labeled it a relatively weak Category 1 storm. In the Saffir-Simpson's shorthand, that warned, in part, of "some damage to poorly constructed signs ... some coastal road flooding and minor pier damage."

By 2 p.m. the next day, however, Charley exploded into a fearsome, 140-mph Category 4. ("Some complete roof failures ... all signs are blown down ... extensive damage ... massive evacuation ... ")

After that, Florida residents especially paid close attention to subsequent media reports of the Saffir-Simpson fluctuations as hurricanes Frances and Ivan approached.

Invented in the 1970s, the Saffir-Simpson scale has a walk-on role in Scott Huler's new book, Defining the Wind. But his focus, his infatuation, is the 1806 Beaufort Wind Scale - the first widely accepted method for judging wind force and the progenitor to all that followed.

The Beaufort scale was created by Sir Francis Beaufort, hydrographer (maritime chart-maker) to the British Admiralty. In an era with no instruments to measure wind speed consistently and reliably, it enabled people to rank the unseen forces of the wind to their observable consequences for life and property.

Beaufort's original scale ranked 13 levels of wind force according to their effects on sailing ships, and the amount of sail ships could safely fly.

Force 1 winds were defined as "Light air, or just sufficient to give steerage way" - that is, just enough wind to move the ship and make the rudder effective. Force 11 winds were "storm" winds, "or that which would reduce her to storm staysails" - only enough canvas to keep the ship under control.

Wind power was as critical to defense and commerce in early 19th-century Britain as fossil fuels are today. Beaufort's scale allowed maritime interests to measure and communicate their experience of the winds with newfound consistency, precision and brevity.

It proved so useful that Beaufort's scale was extended, by others, to other wind effects. One of these permutations focused on the winds' effects on shore - on such things as chimney smoke, trees, roofing slates, pedestrians and their umbrellas.

This was the version of "Beaufort's" scale that Huler first encountered, by accident, in his dictionary. He presumed it was Beaufort's work, and was captivated by it.

"I had never read anything quite like this," writes Huler, whose previous subjects include NASCAR and Continental Airlines. "Here's 110 words and it tells you everything about what the wind can do ... I was so enthralled by it I wanted to read whatever else this master of descriptive prose had written."

At Force 3 - a "light breeze" it said - "wind felt on face; leaves rustle; ordinary vanes moved by wind." At Force 5: a "fresh breeze ... small trees in leaf begin to sway; crested wavelets form on inland waters."

It struck Huler as sheer poetry, and more.

"Language is, at bottom, a tool, a technology for communication," he writes. "And irrespective of its beauty, the Beaufort Scale, in its clarity and specificity, is a spectacularly sharp tool."

But as he pursued the story of the scale and its author, Huler discovered to his dismay that Beaufort didn't actually write this onshore version of the "Beaufort" scale. It turned out to be a derivation that emerged in 1906 - long after Beaufort's death - from the English equivalent of the National Weather Service.

Huler also immersed himself in Beaufort's other writing, and concluded "it's not poetry."

This disappointment threatened to topple the entire romantic premise of Huler's book - that Beaufort, this colorful character, who early in his career tangled with Malay pirates; who was wounded by saber and blunderbuss; who was shipwrecked with the King's treasure and rescued by Capt. William Bligh; who recommended a young Charles Darwin to be the naturalist aboard the HMS Beagle - is improbably remembered best for penning one lean gem of scientific observation and language.

"All was dust," Huler said. "Everything had fallen apart."

Or maybe not. In pursuit of the scale's true lineage, Huler found that Sir Francis' original 1806 product- the less lyrical, utilitarian scale that ranked wind force by its effects on ships at sea - was only a beginning.

Over the years, as technology developed, other contributors took Beaufort's original wind categories and defined them with measured wind speeds, then used them to describe the wind's effect on ocean waves. ("Force 11: Violent Storm; exceptionally high waves; the sea is completely covered with long white patches of foam lying in the direction of the wind. Visibility affected.")

Scientists later created all manner of siblings and cousins. In addition to the Saffir-Simpson Scale, these include:

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