Blown_Away - Blown Away Worldwide deforestation, mining,...

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Blown Away Worldwide deforestation, mining, overgrazing, and the diversion of water have combined to create huge dust clouds that carry bacteria, viruses, soot, acids, radioactive isotopes, and pesticides from Asia and Africa to the United States By Karen Wright DISCOVER Vol. 26 No. 03 | March 2005 | Environment By the time the yellow Haze had reached southern Utah, Marith Reheis was already camped out in Canyonlands National Park and trapping local desert dust for the U.S. Geological Survey. “The weather had been absolutely perfect—not a cloud in the sky,” she recalls. “But that third morning, we saw a patch of sky that just looked weird. It looked like a dust cloud. But there hadn’t really been any change in the wind, and it wasn’t the right color.” The right color would have been grayish white or red, hues typical of dust clouds churned up in the Mojave Desert to the west. Instead, the cloud Reheis saw that morning in May 1998 was the color of mustard. And it wasn’t from the Mojave: When Reheis returned to her office in Denver, she tracked down satellite images on the Internet and learned that the yellow haze had erupted several days earlier over a broad swath of the Gobi Desert in China. It had swept east across 5,000 miles of ocean. Some of it had landed on the West Coast, from British Columbia to California; the rest moved inland in a slow crawl across the continent. Reheis wasn’t the only scientist to notice. Meteorologists, oceanographers, remote-sensing specialists, and air-quality experts—not to mention a few air traffic controllers—had all gotten their first overhead view of an Asian dust storm moving across the Pacific Ocean to North America. The phenomenon itself isn’t new. Massive clouds of sediment have been blowing around Earth ever since there was earth to blow and wind to blow it. But using sophisticated Earth-watching satellites launched in the 1990s, scientists around the world have gained a new appreciation for the global scale of dust movement. For example, NASA’s Total Ozone Mapping Spectrometer, or TOMS, launched in 1996, is the first instrument that can track dust storms over both land and sea. Its sensors can distinguish a dust cloud from a rain cloud, and it operates in real time. The Sea-viewing Wide Field-of- view Sensor, or SeaWiFS, another satellite-borne NASA instrument, transmits images in true, vibrant colors and provides global coverage every 48 hours. Courtesy Seawifs Project, NASA/Goddard Space Flight Center, and OrbImage FROM ASIA WITH DUST   A massive dust cloud from the Asian continent passes  over Japan in April 2002, traveling a major dust byway  that runs east out of the Gobi Desert. Each spring, a  cold air mass called the Siberian High swoops down  on the Gobi and hoists soil particles into the  atmosphere. Uneven heating of the ground and air  generates turbulent airflows that keep sediment aloft.  “A moderately wimpy, sustained wind with turbulent 
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This note was uploaded on 06/09/2009 for the course ISB ISB202 taught by Professor Gabeording during the Spring '09 term at Michigan State University.

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Blown_Away - Blown Away Worldwide deforestation, mining,...

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