Pacifying Ginger

PACIFYING GINGER For two weeks, Hurricane Ginger moved erratically east and west in the mid-Atlantic. Then it stalled, 650 nautical miles off the Florida coast. For the scientists of Project Stormfury, a long wait was over: now they had an opportunity to experiment with and perhaps partially tame a major hurricane while it was a safe distance from populated land areas.

As Ginger hovered indecisively, Stormfury's scientific director, a soft-spoken meteorologist named R. Cecil Gentry, recommended an attack. Taking off from fields along the East Coast, Bermuda and Puerto Rico, 16 planes headed straight into the thick of the storm, the longest-lived hurricane on record. While instrument-packed planes monitored the tricky "bombing" runs, an Air Force C-130 transport and two U.S. Navy A-6 Intruder jets flying at 22,000 feet dropped hundreds of small explosive cylindrical canisters that sprayed tiny particles of silver iodide in the area outside the eye of the hurricane.

Heat Engine. By thus "seeding" Ginger, scientists of Stormfury--a joint Commerce and Defense departments project--hoped to diminish the hurricane's awesome power, equivalent to the wallop of 400 20-megaton hydrogen bombs. Literally a huge heat engine, a hurricane is formed by spirals of warm, moist air rising from tropical seas. As the heat-packed vapor spins increasingly faster, it converges toward the eye of the storm and is forced upward; meanwhile within the eye, the temperature rises and pressure drops. Acting like a chimney, the walls of the warm vortex continue to refuel themselves and add to the storm's fury by drawing still more moisture from the sea.

It was to keep these winds from spiraling inward and increasing their velocity that Stormfury's aircraft dropped silver iodide particles into the colder clouds of water vapor 50 to 110 miles from the eye. Theoretically the vapor would form into ice crystals around the iodide seeds, and the heat released by the crystal formation would raise the temperature in the targeted clouds around the eye. As they heated up, these clouds (called a rainband) would also expand and create new low pressure areas away from the eye. The new regions would, in turn, keep the swirling winds and water vapor from converging on the storm's vortex. Thus. the chimney would be deprived of its vital fuel and the hurricane's energy would be spread over a wider area. The ultimate effect would be to reduce the velocity of the winds.

Hurricanes, however, are notoriously unpredictable. After the first hurricane seeding attempt--Project "Cirrus" by a General Electric group in 1947--the storm suddenly reversed course and slammed into Savannah, Ga., wreaking extensive damage. Although the seeding probably had nothing to do with the change in course, Georgians were so outraged at the scientists that the Government has since forbidden any tampering with hurricanes that are within 18 hours' striking distance of land.

That restriction has limited Storm-fury's activities. Since 1961, only four hurricanes have been seeded. The first two attempts were not noticeably successful, possibly because the planes dropped too little silver iodide too close to the center of the storm. But by the time Hurricane Debbie appeared in 1969, computer simulations at the National Hurricane Research Laboratory in Miami had suggested that seeding would be more effective if the pellets were dropped in a greater quantity and slightly farther from the eye. Using this new approach, the hurricane tamers apparently managed to reduce Debbie's winds by as much as 30 m.p.h.

Somewhat Fickle. Ginger proved to be a more difficult target. Unlike Debbie, which was relatively compact and well formed, the latest hurricane was a huge, sprawling storm that lacked the classic, clearly defined eye and cloud walls. Nonetheless, Stormfury's planes made six successful seeding runs before breaking off the attack when Ginger turned toward the North Carolina coast. By week's end. as Ginger came ashore just east of Morehead City, causing some $1,000,000 damage, Stormfury's scientists had already begun studying data to determine whether the seeding had any real effect. Even if they discover a drop of only 5% to 10% in wind velocities, they will consider it a major achievement. That little a reduction in some future hurricane just about to strike a populated area could save lives and prevent millions of dollars of property damage. But the information gleaned from Ginger is complex and will not be fully deciphered for months. As Gentry's associate director Harry Hawkins once explained: "Stormfury is meteorology's Apollo moon program. The difference is that we won't know for six months whether we've landed or not."

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