Harness lightning for energy, thanks to high humidity?

By David Biello

Eyjafjallajökull-eruption-lightning

Why do the roiling, black clouds of a thunderstorm produce lightning? Ben Franklin and others helped prove that such lightning was discharged electricity, but what generates that electricity in such prodigious quantities? After all, storms generate millions of lightning bolts around the globe every year—even volcanoes can get in on the act as the recent eruption of Eyjafjallajökull did when photographs captured bolts of blue in the ash cloud.
Perhaps surprisingly, scientists still debate how exactly lightning forms; theories range from colliding slush and ice particles in convective clouds to, more speculatively, a rain of charged solar particles seeding the skies with electrical charge. Or perhaps  the uncertainty about lightning formation is not surprising, given all that remains unknown about clouds and the perils of studying a storm—an electrical discharge can deliver millions of joules of energy in milliseconds.
But Brazilian researchers claim that their lab experiments imply that the water droplets that make up such storms can carry charge—an overturning of decades of scientific understanding that such water droplets must be electrically neutral. Specifically, chemists led by Fernando Galembeck of the University of Campinas found that when electrically isolated metals were exposed to high humidity—lots and lots of tiny water droplets known as vapor—the metals gained a small negative charge.
The same holds true for many other metals, according to Galembeck’s presentation at the American Chemical Society meeting in Boston on August 25—a phenomenon they’ve dubbed hygroelectricity, or humid electricity. "My colleagues and I found that common metals—aluminum, stainless steel and others—acquire charge when they are electrically isolated and exposed to humid air," he says. "This is an extension to previously published results showing that insulators acquire charge under humid air. Thus, air is a charge reservoir."
The finding would seem to confirm anecdotes from the 19th century of workers literally shocked—rather than scalded—by steam. And it might explain how enough charge builds up for lightning, Galembeck argues. … Read More>>

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