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5 December 2013 11:26 am ,
Vol. 342 ,
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...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Cloud Mystery Cleared Up
9 April 2002 (All day)
When smoke rises from a chimney, the column soon loses its shape as the smoke wafts skyward. Yet puffy cumulus clouds, which have a similar structure, tower into the sky without breaking apart. Now a researcher claims to have found the answer to this long-standing mystery, and it could have implications that range from weather prediction to pollution control.
A column of smoke is made up of patches of intensely spinning air, or vortices, that suck in surrounding air--a process physicists call entrainment. This outside air tends to disperse the smoke. Previous research showed that how well clouds stick together also depends on entrainment, but the factors that influence this process are poorly understood.
To investigate, Rama Govindarajan, a fluid dynamicist at the Jawaharlal Nehru Center for Advanced Scientific Research in Bangalore, India, created a computer model of cloudlike flow. She found that inside the vortices, ringlike regions sporadically give off heat as the moisture inside them condenses. Giving off heat makes the rings spin faster, which in turn reduces the amount of air they suck into the cloud, Govindarajan reports in the 1 April issue of Physical Review Letters.
"It's been very difficult to reproduce basic cloudlike flows in models so far," says Ganapati Bhat of the Center for Atmospheric and Oceanic Sciences at the Indian Institute of Science in Bangalore. Bhat says such models would be useful for weather prediction. For instance, he says, rain is not as likely from clouds that entrain more air. Govindarajan says the work could also lead to better tracking of smoke from forest fires or other air pollution.
JNCASR Fluid Dynamics Unit