Blue Lightning in the Stratosphere

Aug. 15, 2021: Rain. Clouds. Thunder. The stratosphere has none of those things. Weather up there is pretty dull. Except when the lightning starts….

Researchers call them “blue jets.” The elusive discharges leap into the stratosphere from thunderstorms far below. They are rarely seen, but storm chaser Rob Neep was able to capture some over Sonora, Mexico, on August 3rd:

“I couldn’t believe my eyes,” says Neep, a former TV photojournalist. “I was actually looking for sprites when the jets appeared. They were definitely visible to the naked eye, both my cousin and I observed them.”

Oscar van der Velde of the Lightning Research Group at the Universitat Politècnica de Catalunya watched Neep’s video and says it is “Excellent–perhaps the best example of classic blue jets we’ve seen in a long time!”

First recorded by cameras on the space shuttle in 1989, blue jets are part of a growing menagerie of transient luminous events (TLEs) in the upper atmosphere. They appear alongside sprites, ELVES, and other lightning-like forms. Blue jets, however, seem to be more elusive than the others, often frustrating photographers who try to catch them.

“We’re not sure why ground-based observers see them so rarely,” says van der Velde. “It might have something to do with their blue color. Earth’s atmosphere naturally scatters blue light, which makes them harder to see. Neep’s video was taken from a relatively high altitude site (elevation 3500 ft); thin clear air probably helped.”

“Not all storms have blue jets,” he allows. “Even so, blue jets may be much more common than we think.”

Above: Artist’s concept of a blue jet observed from the ISS. Credit: DTU Space, Daniel Schmelling/Mount Visual

In 2018, SpaceX launched Europe’s Atmosphere-Space Interactions Monitor (ASIM) to the International Space Station to study TLEs from space. Data from ASIM show that blue jets can leap as high as 170,000 feet above the ground. They’re sparked by mysterious “blue bangs“–brilliant blue flashes in the tops of thunderclouds possibly caused by intense turbulence.

It’s important to study blue jets because, according to van der Velde, “there can be considerable production of NOx and ozone by these discharges, potentially affecting the chemistry of the atmosphere.” Also, some blue jets might rise high enough to touch the ionosphere, forming a new and poorly understood branch of the global electrical circuit.

And on top of everything else, “they’re beautiful,” says Neep. “I was lucky to catch some.”

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