Rainmaker Bacteria
Found in Atmosphere
Researchers at Louisiana State University have found evidence of bacteria serving as ice-forming catalysts in precipitation around the globe.

The formation of ice in clouds is important in the processes that lead to snow and rain. Ice nucleating bacteria – which have been referred to as “rain-making bacteria” – may be significant triggers of freezing in clouds and influence the water cycle.

The LSU findings, which help explain how
atmospheric microbes influence the water cycle were, published in the Proceedings of the National Academy of Sciences for the the week of November 17, 2008.

“Our models can accurately predict the concentrations of cells and biological ice nucleators in precipitation using a relatively small number of variables,” said Brent Christner, the assistant professor of biological sciences who led the research team. “The data provides a first glimpse of the conditions that appear to favor the distribution of biological ice nuclei in the atmosphere and will be useful for predicting their abundance in other contexts.”

The study concludes that vegetation and soils are an important source of biological ice nuclei to the atmosphere at some geographical locations. Though they were detected in snow from places as remote as Antarctica, ice nucleating bacteria may also exist in the ocean, or alternatively, are able to travel large distances in the atmosphere.

“The atmosphere provides an efficient conduit for microbial dispersal on a global scale,” Christner pointed out.
“Previous work has shown that microbes can metabolize and grow in clouds, meaning that the atmosphere may represent an environment for life.

“It is possible that cloud-borne microbes could ‘turn on’ their ice nuclear in the atmosphere and subsequently be returned to the ground in snow or rain. This is a very exciting possibility.”

LSU Media Relations

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