06-08-2006 - Earth

sagar: Author=’Abby Frank’ program=’4904′ video=”This map of the Earth shows areas of particularly strong warming of the lower atmosphere in yellow, orange and reddish colors. Note the enhanced warming of midlatitude regions north and south of the equator, indicating the expansion of the tropics. The map also shows pronounced warming at Arctic latitudes._JB:_ This is “Earth & Sky”:/http://208.96.63.114/. Researchers say the warm tropical zone around Earth’s equator has expanded by two degrees of latitude, 140 miles or over 200 kilometers, over the past 27 years.

_DB:_ There are different ways of defining the “tropics,” but meteorologists typically define them as the 30 degrees of latitude centered on the equator. The new research shows that this warm zone at Earth’s mid-section has gotten wider since 1979. “Qiang Fu”:http://www.atmos.washington.edu/~qfu/ is a professor of atmospheric science at University of Washington and leader of the research team. He told EarthSky that satellite data indicate a warming trend in the lower atmosphere over subtropical areas. This warming has made the air in the lower atmosphere expand upwards, in turn pushing the subtropical jet streams toward the poles.

_JB:_ And the shifting jet streams indicates that the warm tropical area between them is expanding. Scientists suspect that global warming or ozone depletion could play a role. Though the changes may seem small, the impacts can be really big, leading to droughts in more heavily populated areas at higher latitudes, according to Dr. Fu.

_Qiang Fu:_ Given other conditions, this would definitely enhance the probability for drought events in the higher latitudes.

_DB:_ Our thanks today “NOAA”:http://www.noaa.gov, the National Oceanic and Atmospheric Administration. Visit us on the web at earthsky.org. We’re Block and Byrd for “Earth & Sky”:/http://208.96.63.114/.

Written by EarthSky