Rainmaking Bacteria Ride Clouds to "Colonize" Earth?

Christine Dell'Amore
National Geographic News
January 12, 2009

Rainmaking bacteria that live in clouds may have evolved the ability to spur showers as a way to disperse themselves worldwide, a recent study found.

The research gives scientists a first glimpse into the link between biology and climate, and into how the tiny organisms globe-trot with the weather cycle.

The microbes—called ice nucleators—are found in rain, snow, and hail throughout the world, according to previous work by Brent Christner, a microbiologist at Louisiana State University.

Christner had shown that, at a high enough concentration, these organisms may be efficient drivers for forming ice in clouds, the first step in forming snow and most rain.

But he hadn't been able to pinpoint their source—until now.

In the recent study, Christner and colleagues found that the critters hail from snow, soils, and young plant seedlings in such such far-flung sources as Antarctica, Canada's Yukon Territory, and the French Alps.

The bacteria may be part of a constant feedback between these ecosystems and clouds.

"This is sending ripples through the atmospheric science community," Christner said.

"This idea would have been viewed as crazy 25 years ago, but these new findings have invigorated research … in the role that biology may play in atmospheric processes."


On the ground, researchers found ice nucleators alongside aerosols—tiny particles suspended in air—that could be chemically traced back to clouds.

In some places, the nucleators had come mostly from soil and plant ecosystems, the results showed.

Continued on Next Page >>




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