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Storm troopers

Scientists turn storm-chasers starting Aug 15 when they stake out some of the world's most violent storms in an international project called the African Monsoon Multidisciplinary Analysis, writes Prakash Chandra.

india Updated: Aug 07, 2006 03:46 IST

Scientists turn storm-chasers starting August 15 when they stake out some of the world’s most violent storms in an international project called the African Monsoon Multidisciplinary Analysis. Using satellites, aircraft and ground-based radars, they will study thunderstorms along the tropical African coast to determine how low-pressure disturbances grow into tropical storms as they cross the ocean. Predicting storms is a nascent science and data from this experiment will help refine computer models of storm behaviour.

Tropical storms are large rotating weather systems in the Atlantic, Indian and Pacific oceans. They are called hurricanes in the Atlantic and eastern Pacific, typhoons (or ‘great winds’, in Chinese) in the western Pacific, and cyclones in the Indian Ocean. During hot months, moisture evaporates from warm oceans near the Equator, rising and condensing into thunderclouds. Cool air rushes in to replace the rising humid air, setting off strong winds that barrel around a low-pressure centre: the ‘eye’ of the storm. As more air is drawn in, the storm turns quicker, like a figure skater spinning faster when she pulls in her arms.

Researchers actually fly aircraft into storms to measure their thermal structure, pressures and wind velocities. From the safety of a cockpit, you see only gray clouds and don’t feel the whipping winds until you reach the ‘eye-wall’ — a ring of thunderstorms around the calm eye. Vertical updrafts and downdrafts then buffet you all the way into the eye, where the sudden tranquillity has to be experienced to be believed: sunshine streams into the cockpit from a circle of blue sky directly above the plane, surrounded by the blackness of the eye-wall. And below, in the ocean, waves topping 60 feet crash into one another.

As tropical storms drift over the ocean, they gain strength from moist air to produce violent winds, torrential rain and high seas. On making landfall, cyclones are cut off from moisture and usually dissipate. But if they don’t, they cause widespread destruction from surging seas, flooded rivers and high winds that erode coastlines and wash beaches out to sea. Aren’t we familiar with the cyclonic fury on India’s eastern seaboard!

Scientists try to tame tropical storms by seeding clouds with dry ice or silver iodide, cooling the ocean with cryogenic material or icebergs, and have even considered blowing them up with hydrogen bombs. Perhaps we should just learn to coexist better with nature’s moods by having strict building codes and evacuation plans for vulnerable coastal areas. If you still choose to live there — you know it comes at a price.

First Published: Aug 07, 2006 01:42 IST