Taming the storm: a hurricane's violent winds can ravage coastlines. Can scientists find a way to stop these devastating storms?
Even as residents of these hurricane-ravaged regions continue to dig out from last year's rubble, scientists are predicting another stormy season this year. Researchers have recorded warmer than average water-surface temperatures in the Atlantic Ocean, which is just one factor suggesting that a higher than average number of hurricanes will develop.
Hoping to save lives and spare further devastation, scientists are going to extremes to fight the powerful storms. Since the 1940s, people have been attempting to devise ways to harness hurricanes--either by sapping their strength or by driving the storms back out to sea.
Many hurricane-controlling ideas evoke images from science-fiction movies. For instance, some people envision building giant fans to blow hurricanes away from shore. Others imagine using bombs to blast the storms out of the water. Although scientists say those particular schemes, are nothing more than wild fantasy, two other proposals have actually been considered. And the U.S.-government even tested one of them on real-life hurricanes. Read on to learn more about these two schemes and find out if either one stands a chance against Earth's most powerful storm
During the Atlantic hurricane season--which runs from June through November--tropical disturbances develop over the ocean's tropical waters. Warm seawater evaporates, or changes from a liquid to a gas, and the newly formed water vapor rises. As the moist air inches upward, it cools and eventually condenses to create liquid water in the form of rain and clouds.
At the same time, the climbing, warm air reduces air pressure, or the force of air pushing on a particular region. Strong winds whip into this low-pressure area. These gusts pull in warm, moist air and help to build more clouds. "The system draws air faster and faster inward, and you begin to form a storm," explains Neal Dorst, a research meteorologist who studies weather at the National Oceanic and Atmospheric Administration (NOAA).
Large-scale winds over the Atlantic drive these disturbances west toward the Caribbean islands and shores in the southeastern United States.
When one of these storms grows stronger--creating a spiraling band of thunderstorms with a central eye (see Nuts & Bolts, right)--a hurricane can form.
As a hurricane cruises over the ocean, it intensifies through the constant input of warm, moist air from the sea surface. "If you could stop this transfer of energy between the ocean and the atmosphere, you could stop a hurricane," says Dorst.
One scheme scientists have considered for stomping out these large-scale storms: Coat sections of the ocean surface with a thin film of oil (see diagram, above). Ships could sail ahead of a hurricane and spread this slick across the sea surface. The oil would keep the ocean water from evaporating. When the hurricane passed over the oil slick, its source of rising moist air would shut off. Winds would die down and the hurricane would break up. After the storm passed, the biodegradable oil would break down into harmless substances.
But most scientists doubt that this plan would work. Once hurricanes get going, 15 meter (50 foot) waves, and winds that can reach 250 kilometers (155 miles) an hour, whip up the ocean like a blender. High waves and fast moving water make it unlikely that a thin layer of oil would stay in place. "And any film that could stand up to that is definitely going to kill fish," says Dorst. "It seems like it would be a horrible ecological mess."
Scientists have never attempted to coat the ocean with oil to stop a hurricane But in the 1960's, the U.S. government sent specially designed aircraft into hurricanes.
The planes flew through the stormy skies toward the eyewall. This circular ring of clouds surrounds the hurricane's center and has the strongest surface winds in the storm. While flying through the band of clouds just outside the eyewall, the Project Stromfury pilots released particles of the chemical compound silver iodide from a plane. The hope? That a special type of water droplet in the atmosphere would freeze onto the particles and cause clouds to grow faster in that area.
How could more clouds help halt a hurricane? Scientists believed that the growth of these clouds would rob energy from the eyewall. Eventually, the growing clouds would spread out and slow the hurricane's winds.
The government tested Project Stormfury on four storms. In some experiments, wind speeds inside the hurricanes did decrease. But most scientist believe the weakening winds were simply part of the hurricane's lack the special type of water droplets needed for the plan to work. "So that theory fell that on its face," says Robert Black, a NOAA research meteorologist. The government ababdoned the project in 1983.
So far, no plan has halted a hurricane in its path. Should scientists stop trying? "It would be better to spend money to armor the houses along the coastline," says Black.
But even skeptics admit that something can be learned from faulty theories. Black says, "It helps you to find out what really affects the storm."
STOP THAT HURRICANE!
Scientists have studied methods that might destroy a hurricane before it reaches shore.
Pilot sprinkled cloud-creating chemicals into hurricanes in the hope that new clouds would rob energy from the storm.
Some scientists think an oil slick would decrease evaporation of seawater--sapping the hurricane's strength.
Nuts & Bolts
1 Hurricanes that strikes the United States and Caribbean are born over warm waters in the Atlantic Ocean. The sun-heated seawater evaporates and creates warm water vapor. As this moist air rises, it cools and condenses--forming rain and storm clouds.
2 As warm air rises, it decreases the air pressure, or the force of air pushing on an area. Warm, humid air from outside the storm zone, rushes in to fill this low, pressure area--causing powerful winds. At the same time, the rotation of Earth on its axis causes the storm clouds to start swirling. In Earth's Northern Hemisphere, this rotation is counterclockwise.
3 The spiraling winds form Circular bands of storm clouds. Eventually, the inner bands wrap around themselves, creating a circular ring of clouds, or eye-wall. A hurricane forms when winds inside the storm reach 119 km (74 mi) an hour. In the hurricane's center, or eye, these winds die out. There, downward-moving winds cause clouds to evaporate, resulting in clearer skies.
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|Title Annotation:||EARTH: HURRICANES|
|Date:||Sep 5, 2005|
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