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My good friend Dave Sands is not only a brilliant biologist -- I
cite him in The Rational Optimist arguing for genetic modification
to improve the quality rather than the quantity of food -- but a
very fine poet. He's profiled in yesterday's New York Times discussing his
latest theory that ice-forming pseudomonas bactera in the air play
a central role in precipitation:
In the last few years, Dr. Sands and
other researchers have accumulated evidence that the well-known
group of bacteria, long known to live on agricultural crops, are
far more widespread and may be part of a little-studied weather
ecosystem. The principle is well accepted, but how widespread the
phenomenon is remains a matter of debate.
If true, this could have all sorts of implications.
The accepted precipitation model is that
soot, dust and other inert things form the nuclei for raindrops and
snowflakes. Scientists have found these bacteria in abundance on
the leaves of a wide range of wild and domestic plants, including
trees and grasses, everywhere they have looked, including Montana,
Morocco, France, the Yukon and in the long buried ice of
Antarctica. The bacteria have been found in clouds and in streams
and irrigation ditches. In one study of several mountaintops here,
70 percent of the snow crystals examined had formed around a
This ability to promote freezing of water
at higher-than-normal freezing temperatures has led Dr. Sands and
other scientists to believe the bacteria are part of an unstudied
system. After the bacteria infect plants and multiply, he says,
they may be swept as aerosols into the sky, where it seems they
prompt the formation of ice crystals (which melt as they fall to
earth, causing rain) at higher temperatures than do dust or mineral
particles that also function as the nuclei of ice
Sands is telling us that the air is a habitat too.
By chance today my son and I were walking in the rain and we
started imagining a future in whcih weather is controllable, but
some countries decide when it should rain by political means --
referendums, committees, bureaucracies, protests -- while others
leave it to the market.
We plan to write a Swiftian satire along these lines. One wet