Report — From the September 1991 issue
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Report — From the September 1991 issue
Atop the IRE Financial Building on Dixie Highway in Coral Gables, Florida, Max Mayfield and I sat one midsummer afternoon before a bank of computer terminals, watching information gush cybernetically into the National Hurricane Center. The data flowed in from land stations, ships, aircraft, radar, buoys at sea; it sprinkled down from helium balloons and geostationary satellites into the Cadillac of supercomputer animation systems, McIDAS (for Man-computer Interactive Data Access System). On the screen we were looking at, the North Atlantic was expressing itself in a language of heat, pressure, and motion, and McIDAS was translating this biospheric oratory into data-generated pictures, images we could enhance to our heart’s content. Were we watching a hurricane form? We didn’t know yet. What was certain was that the season of volatility had begun, an anxious time meteorologically and also psychically — a time when people along the Gulf of Mexico, the Eastern seaboard, and, to the south, on the islands of the Caribbean live in real fear of being visited by sudden, violent catastrophe.
A hurricane is the Atlantic (and northeast Pacific) version of a tropical cyclone. Because warm water is the essential ingredient of hurricanes, these storms tend to originate in relatively quiet, equatorial waters. For the most part, they are a major factor only in the western Pacific, where they are called typhoons; in the Indian Ocean, where they are simply called cyclones; and in the warmer waters of the North Atlantic, where they derive their name from the Carib Indian word huracan, “big wind.” Although it is not known precisely why hurricanes form, forecasters such as Mayfield do know that these whirlwind fevers that cool our overheated planet develop from smaller tropical storms that whip up in the doldrums west of the Cape Verde Islands.
On the computer’s large screen, a sequence of schematic riffs — elongated inverted Vs, representations of low-pressure zones — staggered out across the doldrums, where, from late June through mid-November each year, the north-inclined sun brews the indigo surface waters beyond 80 degrees Fahrenheit. Above the water, trade winds that have whipped off the coast of northwest Africa tangle with those blowing up from the southern hemisphere. These convulsing and contradictory winds agitate the heat-sponsored Atlantic anger, urging it toward the surface and into a vaporous rage.
Mayfield, pointing to the screen, called my attention to how, within one of the low-pressure troughs, the July sun had simmered the surface waters enough for moisture-laden air to quicken its rise; it was being sucked up into clouds. He switched McIDAS to its time-lapse satellite picture loop and highlighted the thermal properties of the increasingly unstable storm: warm cores of luminous reds, oranges, yellows; mantles of refreshing greens and blues where rain was falling. New data threaded into the machine. The moisture-rich trough we were observing bloomed splatters of aspiration, graphic popcorn — thunderstorms. What was previously a tropical disturbance, with lazy 8- to 18-mile-an-hour winds, had intensified. Vertical columns of scattered cumulus — puffs of steam updrafted off the ocean, cooling into rain as they expanded — had coalesced, swollen together, to create a tropical depression, their combined winds (up to 38 mph) declaring a fragile confederation.
While the prevailing winds carried the storm from east to west/northwest, the west-to-east rotation of the earth rubbed against the storm with a soft friction, like a flywheel or a gear set perpendicular to the heaped plate of the weather system, causing it to slowly spin counterclockwise in a spiral twist. This was one of the signs that a sizable tropical storm might be stewing. Known as Coriolis, or deflecting, force, the earth’s rotation also inspires the ocean currents to circulate, redistributing the heat accumulated in warm tropical waters. In the weather system we’d been monitoring on McIDAS, the clouds had assembled into an inward-turning pattern, a merry-go-round of brisk winds and rainsqualls, and the system’s isobars — lines of equal pressure — formed awkward concentric rings, like an asymmetrical onion. (The closer the isobars are packed together, the fiercer the speed of the winds.) Now, if a vortex deepened at the center of the storm and if the clouds walled up into an eye, forming a chimney for evaporating water to be sucked heavenward off the ocean — if these things happened, we’d have a hurricane: a massive, self-sustaining heat engine, siphoning excess warmth out of the ocean and taking it on a parabolic ride west and north, its intention to balance the earth’s heat budget, spreading around the surplus at cooler latitudes. A well-developed hurricane is able to maintain its whirling, feverish tantrum because warm, moist air, as it condenses, releases latent heat — an explosive fuel.
Hurricanes, tropical cyclones everywhere in the world, are by far the worst storms in nature’s portfolio. Full-blown hurricanes are typically one hundred times larger than a thunderstorm; every minute they release energy equivalent to a hydrogen bomb. A hurricane’s nearly inconceivable force is perhaps easier to grasp if converted to a measurement of electrical power: An estimated 16 trillion kilowatts are produced by a hurricane in a single day. At such a rate, about an hour of hurricane energy would be sufficient to supply all the electric power generated in the United States during the course of a year.
About 90 percent of a hurricane’s energy is continuously converted as the water vapor vacuumed up through the hurricane’s eye expands at higher altitudes, chills, and then condenses into rain, which falls in buckets, barrels, tanker-loads: An average hurricane precipitates approximately 2 billion tons of water a day. Only in the matter of wind speed is a hurricane outdone by other weather systems. Hurricane winds begin, on the Beaufort scale, at a feeble 74 miles an hour and rarely exceed 150. Very weak tornadoes clock at 40 mph; more likely, they twist at between 200 and 300 mph, with maximum wind speeds said to approach the speed of sound (761.6 mph).
Nevertheless, the Labor Day hurricane that struck the Florida Keys in 1935, the most prodigious tropical cyclone on record in the United States, manufactured winds in excess of 200 mph, rendering the night air a blur of effervescent fire. The sandy topsoil of the Keys had been blasted airborne off its coral foundation; the quartz particles collided with each other, discharging electricity. Without shelter, anything alive in the middle of such a scourge didn’t stay alive for long.
“Several people were sandblasted to death,” Mayfield told me — well, not with relish, but clearly the details intrigued him. Mayfield’s a former Oklahoma weather nut who, “being smart enough to learn calculus and dumb enough to work the midnight shift,” fit right in as a hurricane specialist at the NHC. “They just found their shoes and belt buckles,” he said, their existence nicked away, molecule by molecule, and zipped into the atmosphere.
Mayfield went to his files for a photograph, shot years ago in the aftermath of a Caribbean hurricane. A 1- by 3-inch pine board, maybe 10 feet long, had been speared dead center through the trunk of a palm tree — a trick customarily regarded as the signature of a tornado. Then again, tornadoes often run in savage packs on the fringe of hurricanes, taking advantage of the unstable conditions. Hurricane Beulah (1967) whisked up 115 of them. In 1969, more than one hundred tornadoes paved the route inland for Hurricane Camille. Her winds, estimated at 190 mph, brought ashore 8 inches of rain and tides more than 20 feet above normal, decimating towns; 256 people died.
Hurricane winds also bear responsibility for some of the tallest waves known on Earth, frequently lashing open-ocean swells to heights of 40 to 50 feet. “I am more afraid of West Indian hurricanes than I am of the entire Spanish Navy,” confessed President William McKinley at the outbreak of the Spanish-American War, acknowledging the truth that throughout history weather had sent more ships to the bottom than warfare. Thus, in 1898, a hurricane-warning network was established in the West Indies by a federal Weather Bureau itself only eight years old.
Even in the hurricane’s eye — the beguilingly serene oculus of the storm, a core sample of a quiet sunny day — all is awry. As winds and enormous bands of rain clouds spiral inward and wall up into a monstrous chimney-like tower of weather, air pressure plummets to its nadir, shaving the full weight of gravity by 70 pounds per square foot for each inch subtracted from the barometer. During 1988’s Hurricane Gilbert, which registered the all-time lowest sea-level barometric reading for this hemisphere, roughly 280 pounds of air pressure vanished up the eye. In this unbearable lightness, eardrums strain and pop; capillaries swell, bringing to the mouth, some victims say, a taste of blood. It is a vortex so ravenous the sea itself lifts upward, creating a blister on the surface some 5 to 15 feet above the already exaggerated tide — with Camille it was 25 feet! — and hauling the dome ashore in a storm surge so abrupt its victims are swallowed like a biblical army, trapped in the middle of joining seas. Beach houses are there and then gone. Buildings lose their structural integrity and collapse within minutes. People hunker down in emergency shelters, or drown.
Before leaving the center that afternoon, I asked Mayfield to put a price tag on the damage should a major Camille-like hurricane strike southern Florida today. He quoted the figure everybody’s using to communicate the seriousness of such an event — $10 billion, minimum.
And the chances of such a strike? Mayfield would rather not think about it. “There’s been so much development on the United States coast,” he said. “People are not going to believe the destruction.”
During hurricane season, the promiscuous, overheated North Atlantic gives birth to a tropical disturbance every three to five days, from eighty to one hundred a season. Not a big deal. The one we had in sight thanks to McIDAS decayed within twenty-four hours, guillotined by the fair, dry weather kingdom known as the Bermuda high. But of every ten tropical disturbances, one exhibits the sporting desire for fame, puts its foot down on the accelerator, and matures into a tropical storm, its winds reaching 39 to 73 mph. It earns a chummy name, becomes an object of attention, a personality. On average, each year six of these rising stars become celebrities — become hurricanes — by virtue of their furious tenacity, in their spectacular lust (or hatred) for heat. In the secret lives of storms, heat is everything. In their public lives, all is cold, cruel destruction.
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