“Is there a connection between cloud formation and cosmic rays coming from galactic sources? This question has an impact on weather modeling, and new experiments are just starting to yield answers,” writes Dr. Kenneth Hicks, Ohio University Professor of Physics, in the June 29 Columbus Dispatch.
“We know that clouds form around seeds that are made up of microscopic particles that float around in the atmosphere. On its own, water vapor will not spontaneously condense into clouds without the help of aerosol seeds.
“About half of these aerosol seeds come from known sources, such as sea spray or dust storms. The other half come from a process called ‘nucleation,’ in which molecules cluster and grow large enough to form seeds for cloud formation,” Hicks writes.
“According to the Intergovernmental Panel on Climate Change, the formation of aerosol particles and how these affect cloud formation are some of the greatest uncertainties in current climate models. Because cloud cover generally has a cooling effect on the atmosphere, it’s important to know how clouds form.
“One hypothesis, which can be traced back at least to the mid-1960s, is that cosmic rays provide a mechanism to enhance aerosol nucleation and, hence, cloud formation,” he continues.
But recent experiments at the CERN accelerator in Switzerland did not support that hypothesis.
“This is a classic tale of the scientific method. Although the CLOUD experiment started with the hypothesis that cosmic rays might enhance cloud formation, and initial experiments suggested this might be the case, further experiments under more-realistic conditions rejected this hypothesis,” he says.
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