In a scene no human could have witnessed, an apocalyptic agglommeration of lightning bolts illuminates an ash cloud above Chile's Puyehue volcano (map) on Sunday.
The minutes-long exposure shows individual bolts as if they'd all occurred at the same moment and, due to the Earth's rotation, renders stars (left) as streaks. Lightning to the right of the ash cloud appears to have illuminated nearby clouds—hence the apparent absence of stars on that side of the picture.
After an ominous series of earthquakes Saturday morning, the volcano erupted that afternoon, convincing authorities to evacuate some 3,500 area residents. Eruptions over the course of the weekend resulted in heavy ashfalls, including in Argentine towns 60 miles (a hundred kilometers) away
Snap, Crackle, Pop
Photograph by Ivan Alvarado, Reuters
Lightning crackles around a miles-high ash plume above Chile's Puyehue volcano (map) on Saturday.
A volcanic lightning storm isn't "unlike a regular old thunderstorm," Martin Uman, a lightning expert at the University of Florida in Gainesville, told National Geographic News in 2010.
The same ingredients are present: water droplets, ice, and possibly hail—all interacting with each other and with particles, in this case ash from the eruptions, to cause electrical charging, Uman said. (See pictures of a volcanic lightning storm in Iceland.)
Night Lights
Photograph by Daniel Basualto, European Pressphoto Agency
Illuminated and electrified by lightning, a roiling ash and gas plume rises over Chile's Puyehue volcano (map) Sunday.
There may be as many as three distinct types of volcanic lightning, volcanic seismologist Steve McNutt told National Geographic News in 2010.
Large, spectacular "natural fireworks" sometimes accompany eruptions, along with an intermediate type, which shoots up from a volcano's vents and reaches lengths of about 1.8 miles (3 kilometers), and finally bolts that can be as short as about three feet (one meter) long and last just a few milliseconds.
source :http://news.nationalgeographic.com
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