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Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Acid Antifreeze in the Atmosphere
23 January 2004 (All day)
Supercold cirrus clouds aren't as frosty as they should be, and nitric acid may be to blame, says a team of researchers. In extremely cold cirrus clouds, nitric acid seems to interfere with ice formation, causing more water to remain as vapor than would be expected. The find puts a kink in climate models and hints that nitric acid from human pollution might be tweaking the cloud cover.
Cirrus are among the highest, coldest clouds, forming 8 to 16 kilometers up. These feathery wisps of ice cover huge areas of the planet, and no climate model would be complete without them. They reflect away solar energy that would otherwise warm the Earth, and they absorb and then reemit heat from Earth back to the ground. But climate modelers may be missing important information about cirrus clouds, according to a paper in the 23 January issue of Science.
David Fahey, an atmospheric scientist at the National Oceanic and Atmospheric Administration in Boulder, Colorado, and his colleagues flew on a plane high into the troposphere, 16 kilometers above southern Florida. They collected samples from cirrus clouds and analyzed them onboard. Back on the ground they noticed something peculiar in their data: Cirrus clouds warmer than -71°C were roughly half water vapor, half ice; but clouds colder than -71°C had much more vapor than expected. That suggested the clouds contained some sort of antifreeze. Fahey and his colleagues suspected it could be nitric acid.
At -71°C, nitric acid forms crystals similar to those of water ice. Fahey and colleagues speculate that these nitric acid crystals interfere with water molecules trying to glom onto ice crystals. It's not clear how much of this high-altitude nitric acid comes from pollution says Fahey. Nitric acid has many sources, from soil bacteria to lightening, but cars and trucks spew significant amounts.
Stephen Wood, a planetary scientist at the University of Washington, Seattle, says the research is exciting and hopes that climate modelers will take notice.