Giant Atmospheric Brown Cloud Has Intercontinental Reach
NASA scientists announced a giant, smoggy atmospheric brown cloud, which forms over South Asia and the Indian Ocean, has intercontinental reach. The scientists presented their findings today during the American Geophysical Union Fall meeting in San Francisco.
A dense blanket of polluted air hovers over central eastern China. The 'Giant Brown Cloud' is an unhealthy mix of ozone, smoke, and other particles from human activities. (Credit: NASA/ORBIMAGE)
The scientists discussed the massive cloud's sources, global movement and its implications. The brown cloud is a moving, persistent air mass characterized by a mixed-particle haze. It also contains other pollution, such as ozone.
"Ozone is a triple-threat player in the global environment. There are three very different ways ozone affects our lives," said Robert Chatfield, a scientist at NASA's Ames Research Center, Moffett Field, Calif. "A protective layer of good ozone, high in the atmosphere, shields us from deadly ultraviolet light that comes from the sun. Second, bad or smog ozone near the surface of Earth can burn our lungs and damage crops. In our study, we are looking at a third major effect of ozone, that it can warm the planet, because it is a powerful greenhouse gas," Chatfield said.
"We found both brown cloud pollution and natural processes can contribute to unhealthy levels of ozone in the troposphere where we live and breathe. Some ozone from the brown cloud rises to high enough altitudes to spread over the global atmosphere," Chatfield explained. Ozone from the Earth's protective stratospheric layer, produced by natural processes, can migrate down to contribute to concentrations in the lower atmosphere, according to the scientists.
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http://www.sciencedaily.com/releases/2004/12/041217100237.htm