Flashes this big might explain the 300,000-volt difference between the ionosphere and the ground
A sprite is like a blue jet but travels the other way.
© Uni. Alaska Fairbanks
Blue jets connect Earth’s electric circuit.
Video images captured in Puerto Rico suggest that blue flashes of light, much like lightning, feed energy from thunderstorms up into the Earth’s ionosphere - a blanket of electrically charged air some 70 kilometres above the ground1.
Some researchers suspect that such phenomena may also fix nitrogen for plants to use and interact with the ozone layer2.
Sprites, elves, trolls and pixies
In the past decade, high-speed, light-sensitive cameras have allowed scientists to describe a menagerie of electrical phenomena, which bear names that would be more at home in a Tolkien novel than a physics textbook. Sprites, blue jets and associated flashes called elves, crawlers, trolls and pixies are all fleeting electrical discharges that accompany thunderstorms.
All these phenomena are hard to spot, as they last for less than a blink of an eye and are obscured from below by cloud. They can be glimpsed along storm fronts and from aeroplanes flying above the clouds.
Sprites, which might also help to maintain the GEC, work a bit like blue jets in reverse. They are pink, or sometimes red, and occur when current from just below the ionosphere moves downwards towards thunderstorms. As with jets, this current excites atoms along the way, causing them to emit light.
TOM CLARKE | © Nature News Service
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