The coolest article i've read anywhere this year (so far!)

When Life Goes Cloudy
[the following are just tasty morsels -- the whole thing is worth reading, not too long: go to http://judson.blogs.nytimes.com and scroll down to 2-19-08]
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"All of which raises some fascinating questions. First: have some microbes evolved to enhance the chances that they will be lifted up, up, up, and away? Certainly, microbes differ in their ability to become airborne. Some are, for example, much more likely to be collected onto bubbles moving up through the water of a lake or the ocean, and thus to be lofted when the bubble reaches the surface and bursts.

Second: to what extent do microbes contribute to the formation of clouds? Clouds form when water droplets cling to particles in the air, such as dust or salt or ash — or microbes. (There would be clouds even without microbes; but that doesn’t mean microbes don’t play a part, perhaps an important one. Especially if they can make clouds form at higher temperatures than they otherwise might.) Is it the case that some microbes have even evolved to promote cloud formation?

Finally: do cloud-borne microbes have an impact on the chemistry of the atmosphere? Up to now, it’s been assumed that atmospheric chemistry is affected by physical and chemical processes, not biological ones. But that assumption may be wrong. Tentative but mounting evidence suggests that cloud dwelling microbes may indeed biodegrade some of the compounds in the atmosphere. This could alter the composition of rain and snow; but more important, microbes could be affecting the chemical composition of the atmosphere itself."

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[in Judson's end notes --]
The idea that microbes might have evolved to make clouds was first suggested to me some years ago by my PhD supervisor, the late W. D. Hamilton; his ideas are outlined in Hamilton, W. D. and Lenton, T. M. 1998. “Spora and Gaia, how microbes fly with their clouds.” Ethology, Ecology, and Evolution 10: 1-16.