June 3, 2009

Air France Jet Vanished In Area Known For Massive Storms

Experts say a nearly continuous band of colliding weather systems near the equator has been the birthplace of some of the world's strongest storms.

Scientists call the region the Intertropical Convergence Zone, where winds from the northern and southern hemispheres clash. This mixture spawns violent thunderstorms that can tower up to 60,000 feet.

Such storms are far higher than any commercial airliner could fly over and officials suspect the Air France jet carrying 228 people that crashed into the Atlantic Ocean on Sunday night between Brazil and Africa may have run into trouble as it crossed into this zone.

Some suspect the plane may have passed into a 400-mile-long cluster of developing thunderstorms with lightning and 100 mph updrafts, according to reports.

This stormy weather band that experts refer to as the ITCZ wraps some 25,000 miles around the world, generally hugging the equator. The ITCZ is similar to the ocean current because it is fluid in its movements as the seasons change, causing it to shift several degrees north and south.

Henry Margusity, a senior meteorologist for AccuWeather.com, said that while the region can be quiet and calm, it is also "the birthplace of our strongest storms on Earth."

The intense sun and warm water in the tropics along the equator heat the air, making it buoyant and sending it upward as the north and south trade winds collide. The convergence of weather from opposite hemispheres fuels the zone's production of thousands of small storms that can merge to form continuous bands of massive ones.

"If you fly an aircraft into a huge thunderstorm, you may not make it out. That's a potential hazard and that's why pilots don't fly into thunderstorms, period, but they're certainly more prevalent along the equator," Delta Air Lines pilot Keith Rosenkranz told the Associated Press. Rosenkranz has flown through this region a few dozen times.

He said the area sometimes sees hail that is blown 10, 20, even 50 miles away toward an aircraft.

Larry Burch, deputy director of the Kansas City, Mo.-based Aviation Weather Center, a branch of the National Weather Service that issues daily weather advisories for pilots, still believes a plane crash caused solely by a storm in that zone is rare.

Burch said thousands of flights travel across this stormy equatorial region worldwide every year without incident and that anytime a flight goes from Australiato Los Angeles, for instance, it crosses into the zone.

"For the most part, a pilot is not going to fly right into a thunderstorm ... They know these conditions are always there," Burch said.

He said he just isn't sure what happened on Sunday night.

Richard Pasch, a senior hurricane specialist at the National Hurricane Center in Miami, said the ITCZ is certainly thought of as a hazard, but it's not normally thought of as life-threatening.

"But strong thunderstorms are an aviation hazard, period," he added.


Image Caption: The thunderstorms of the Intertropical Convergence Zone form a line across the eastern Pacific Ocean. NASA


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