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Weather Bacteria
11/27/2002
Listen in RealAudio 
Is the weather bugging you? Maybe it's because of bugs. Hi, I'm Bryan Yeaton and this is The
Weather Notebook.
There's a study going on in England to examine whether microscopic critters play a role in
where it rains and doesn't rain. We've known for a long time that water droplets and ice
crystals can't form a cloud out of thin air. You need to have nuclei -- something on which
rain or ice can form. It could be a mote of dust, a grain of salt, or a bit of soot.
Anything tiny that attracts water can serve as a cloud condensation nucleus or an ice
nucleus.
It turns out that ice loves to form on some common bacteria, including a few of the Fusarium
and Penicillium species. This ice-forming skill may help the species attack plants by
encouraging frost damage. These bacteria can also be lofted high into the air. The big
question is whether they serve as ice nuclei once they're there.
A study led by the British Center for Ecology and Hydrology and the University of East London
is trying to find out. They're collecting fog droplets from a Scottish hillside and will soon
be flying into clouds. The goal is to verify that ice-loving bacteria actually make it into
rain or snow. Some of the researchers are looking at an even bigger picture. They think
evolution might be prodding microbes to help form ice, clouds, and rain for their own
survival. If bacteria do help build clouds, then the subsequent rain or snow could help the
bacteria disperse far and wide and help it thrive. So the next time it rains, cats and dogs
may have some company in the rain drops.
Bob Henson, author of "The Rough Guide to Weather," brought us this story. The Weather
Notebook comes to you through grants by the National Science Foundation and Subaru of America.
Thanks today to Assistant Producer Doug Sanborn.
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