Another link for your viewing enjoyment:
http://www.hindustantimes.com/news/1...5,00040003.htm
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Climates in cities changing: Research
Asian News International
Washington, December 13
New evidences from satellites, models, and ground observations reveal urban areas, with all their asphalt, buildings, and aerosols, are causing major impact on local and global climate processes.
This was revealed by some of the world's top scientists convening in a special session at the Fall Meeting of the American Geophysical Union in San Francisco recently.
Dr J Marshall Shepherd of NASA's Goddard Space Flight Center along with Steve Burian of the University of Utah, used the world's first space-based rain radar, aboard the Tropical Rainfall Measuring Mission satellite, and dense rain gauge networks on land to determine that higher rainfall rates during the summer months downwind of large cities like Houston and Atlanta.
They offer new evidence that rainfall patterns and daily precipitation trends have changed in regions downwind of Houston from a period of pre-urban growth, 1940 to 1958, to a post-urban growth period, 1984 to 1999.
Cities tend to be one to 10 degrees Fahrenheit (0.56 to 5.6 degrees Celsius) warmer than surrounding suburbs and rural areas. Warming from urban heat islands, the varied heights of urban structures that alter winds and interactions with sea breezes are believed to be the primary causes for the findings in a coastal city like Houston.
Dr Daniel Rosenfeld at Hebrew University in Jerusalem reveals the increased amount of aerosols, tiny air particles, added by human activity to those naturally occurring also alter local rainfall rates around cities.
The particles provide many surfaces upon which water can collect, preventing droplets from condensing into larger drops and slowing conversion of cloud water into precipitation, Rosenfeld added.
In summer, rain and thunder increases downwind of big cities, as rising air from urban heat islands combines with 'delayed' rainfall resulting from the presence of aerosols, creating bigger clouds and heavier rain.
"The space-borne instruments on Terra, Aqua, TRMM, and Landsat provide a wealth of new observations of aerosol particles near and downwind of cities, the cloud optical properties, and surface reflectance characteristics that can help us understand the effects that urban environments have on our atmosphere and precipitation patterns," Dr Michael King, NASA Earth Observing System Senior Project Scientist, said.
NASA's Earth Science Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather and natural hazards using the unique vantage point of space.
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Whether we're arrogant about it or not, our actions DO have consequences.
MB