Wind is simple. It is nothing more than air moving between zones of high pressure and low pressure, traveling in a straight line until
deflected by the rotation of the earth. Unfortunately things get very complicated after that, as Marq de Villiers explains in Windswept: The Story of Wind and Weather, his lively, engaging treatise on wind and the weather it makes.
The devil is in the details. As it moves across the earth, wind takes innumerable local detours and appears in a thousand guises, like the sirocco that blows sand from the Sahara as far north as Britain, the mistral that rips tiles off
Provencal roofs, the foehn that whistles through the Alps.
Everywhere felt but nowhere seen, wind can be the merest whisper, barely powerful enough to scatter the seeds of a dandelion, or it can blast with mind-numbing fury, taking the form of a cyclone, tornado, waterspout or hurricane. A hurricane that today would be classified as Category 5 struck the Florida Keys in 1935 and sandblasted some of its victims into particles, leaving only bones, leather belts and shoes.
Like other "ingredient" books, which treat single topics -- like codfish, oak or clay -- almost as if they were biographical subjects, Windswept serves up a little
history, a fair amount of science and many colorful stories. De Villiers, the co-author of Sahara and Sable Island, blends these elements with a skillful hand.
He explains the science clearly, and he describes the workings of wind, weather and the natural world with enormous gusto. He is a greedy observer, with plenty of wind and storms to watch from his seaside home in Eagle Head, Nova Scotia.
Simply as a catalog of statistics, Windswept is a grabber. In one day a moderate hurricane releases the energy equivalent of 400 20-megaton nuclear bombs: enough, if converted to electricity, to power New England for a decade. Even during a powerful storm, in an open field with no obstructions, the wind velocity at ground level is zero. Fungal spores and bacterial cysts riding on African sand travel as far as the Caribbean, where they are destroying coral. That same dust accounts for the red sunrises in Miami.
Wind is perplexing and always has been. Aristotle was stumped. He argued that it was absurd to think that wind was flowing air. That would mean that all winds were one wind since all air is one air, a self-evident absurdity, like saying that all rivers are the same river. As late as the 17th century, Martin Lister proposed that the trade winds were caused by the breathing of seaweed.
Sailors, for their part, ignored the philosophers and developed a rough, practical understanding of winds and storms. Columbus, after experiencing just one hurricane in the Caribbean, knew enough to recognize the warning signs of the second one. But
neither he nor anyone else understood that weather traveled. "Even the most apocalyptic storms were thought to develop, wreak havoc and then dissipate, in one place," De Villiers writes.
In time, scientists mapped the winds. But the complex inter-actions of wind and weather, and the maddening unpredictability of both, still keep them busy. The broad patterns are fairly well understood, but in a sense all weather is local. On Corsica, in the Mediterranean, to take a striking example, there can be gale-force winds on its west coast while the east coast is calm and an unrelated gale blows in the Strait of Bonifacio, three places only a dozen kilometers apart.
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