Bacteria may cause rain, snow, and hail

MSNBC : Researchers in the growing field of bioprecipitation believe that bacteria may be what triggers rain, snow, and even hailstorms, writes Jennifer Welsh for MSNBC. Although minerals or other particulates have long been thought to cause water droplets to form, for that to happen the water needs to be much colder than is usually found in clouds. Alexander Michaud of Montana State University, who examined golf-ball-sized hailstones, found large amounts of bacteria at their centers. Brent Christner of Louisiana State University and his coworkers studied the plant pathogen Psuedomonas syringae and found that it plays an important role in snow formation all over the world, even in Antarctica; it is very good at creating ice at temperatures above the normal freezing point of water. An organism that lives on a plant, says Christner, would probably seek another plant on the ground. He adds that if it has “the ability to produce precipitation, fall down and land on a plant, [that] could be a cycle.” Both Michaud and Christner presented their findings Tuesday at the general meeting of the American Society for Microbiology in New Orleans.