Air pollution causing stronger cyclones
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China.org.cn, November 9, 2011
Air pollution from soot and aerosol emissions is making cyclones over the Middle East and South Asia more destructive, according to a study.
Natural differences in wind speed and direction over different heights in the atmosphere, known as 'wind shear', normally keep cyclones in check — effectively tearing the storms apart before they reach a certain size.
But emissions from sources such as biomass burning and diesel vehicles have interfered with wind patterns, reducing wind shear and enabling cyclones to grow twice as intense, according to a study published in Nature last week (3 November).
Researchers compared cyclones that occurred between 1979 and 1996 with those between 1997 and 2010. They found that the more recent ones were up to three times more intense, with higher wind speeds — and five of the strongest storms during the period occurred after 1998. Meanwhile, wind shear dropped in this latter period.
