Not Soot And Dust, But Bugs Serve As Nuclei For Raindrops
Jim Robbins

Bozeman (Montana): Walking across the campus of Montana State University here, David Sands, a plant pathologist, says the blanket of snow draped over the mountains around town contains a surprise. The cause of most of it, he said, is a living organism, a bacterium, called pseudomonas syringae.