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 BOTH SIDES OF CLOUDS 



Until recently, given their ephemeral existence, clouds were regarded more as 

 passive indicators of short-term weather rather than driving forces of long-term 

 climate. Only now are researchers beginning to appreciate the degree to which 

 clouds determine how much sunlight the Earth accepts or rejects and how much 

 heat it yields back to space. That is what motivates researchers at the Scripps 

 Institution of Oceanography's C4: Center for Clouds, Chemistry, and Climate. C4 is 

 a multi-institutional. National Science Foundation Science and Technology Center, 

 that studies clouds with satellites, sensors, and spy planes, trying to understand the 

 role that clouds play in controlling climate. 



Although at amy moment they can cover as much as three-quarters of the Earth, 

 clouds remain a mysterious factor in projecting climate. They both heat and cool 

 the planet, and it is unknown which side of their nature will prevail as the climate 

 changes. New research by CA scientists found that clouds in the tropics trap about 15 

 to 20 times more solar energy than previously believed. This is significant because 

 the tropics are a major determinant of global climate and atmospheric and ocean 

 circulation. This finding may require major revisions of models used to predict 

 global climate change. 



C4 scientists are also researching air pollution in California and major metropolitan 

 aieai, around the globe, such as Mexico City and Beijing. They are studying the role 

 that sulfur compounds and certain other polluting chemicals may play in the 

 formation of clouds. They are also trying to understand the affects of global 

 warming on regional weather and climate in Califorrda and the Midwest. If global 

 warming occurs, these areas are projected to exp>erience reduced rairifali and warmer 

 temperatures, shifting agricultural zones northward. 



SCRIPPS INSTITUTION OF OCEANOGRAPHY 

 UNIVERSITY OF CALIFORNIA, SAN DIEGO 



