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6 March 2014 1:04 pm ,
Vol. 343 ,
Since 2000, U.S. government health research agencies have spent almost $1 billion on an effort to churn out thousands...
Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
Antiretroviral drugs can protect people from becoming infected by HIV. But so-called pre-exposure prophylaxis, or PrEP...
Two studies show that eating a diet low in protein and high in carbohydrates is linked to a longer, healthier life, and...
Considered an icon of conservation science, researchers at World Wildlife Fund (WWF) headquarters in Washington, D.C.,...
The new atlas, which shows the distribution of important trace metals and other substances, is the first product of...
Early in April, the first of a fleet of environmental monitoring satellites will lift off from Europe's spaceport in...
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ScienceShot: Broadcast From On High
20 December 2012 12:15 pm
Red sprites, the enigmatic electrical discharges that sometimes occur high over thunderstorms in the wake of strong lightning strikes in the lower atmosphere, can emit low-frequency radio waves, a new analysis suggests. Most work on sprites—fan-shaped, fireworklike flashes that last no more than a few millisecond—hasn't noted such emissions, possibly because researchers weren't looking for them. In the few studies that have detected them, the research hasn't definitively identified the short-lived sprites (denoted by an arrow in this image taken from the International Space Station over southeastern Asia) as the source. Now, analyses of how highly charged molecules generated by sprites would behave suggest that individual, kilometers-long streamers within sprites—somewhat analogous to single bolts of lightning—could indeed act as antennas, generating radio waves at many different frequencies. At an altitude of 75 km, streamers would emit radio waves at frequencies below 3 kilohertz, or 3000 cycles per second, the researchers reported last month in Geophysical Research Letters. A sprite streamer at an altitude of 40 km, where the atmosphere is much thicker, might generate radio waves with frequencies up to 300 kHz. Also, the team estimates, the stronger the electric field in a sprite, the higher the frequency of radio emissions will be.
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