SPACE - Danish experiment suggests unexpected magic by cosmic rays in cloud formation

According to the theory, small clusters of molecules in the atmosphere have difficulty growing large enough to act as "cloud condensation nuclei" on which water droplets can gather to make our familiar low-altitude clouds. The SKY2 experiment shows that the growth of clusters is much more vigorous, provided ionizing rays—gamma rays in the experiment or cosmic rays in the atmosphere—are present to work their chemical magic. Details of the experiment appear in the latest issue of Physics Letters A.

http://phys.org/news/2013-09-danish-unexpected-magic-cosmic-rays.htm