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Aug 4th 2021

Blue Jet Lightning: Exploring the Secret Lives of Thunderclouds

When it comes to weirdness, our world never disappoints. Just when we think we have things figured out — bam! — there’s suddenly upside-down bursts of blue jet lightning streaming into the stratosphere. Thankfully, science is on the case. Using instruments on the International Space Station (ISS), astronauts were able to track down the spark that sets off this azure atmospheric occurrence.

Blue Jets: Such a Bright Thing

Terrestrial lighting is a commonplace and relatively well-understood phenomenon. These everyday electrical discharges occur between oppositely charged endpoints — usually storm clouds and the ground — and release up to 1020 worth of electrons. There’s even a supercharged form known as “superlightning” that packs a punch equivalent to that of a low-yield nuclear weapon. Yikes.

However, blue jet lightning is something else entirely. As Science News notes, this type of lightning arcs up into the stratosphere instead of down toward the ground and glows blue instead of white. The color palette comes down to gas excitement: On its way to Earth, typical lightning excites a host of gases simultaneously to create a white or yellowish light. But as these jets streak into the stratosphere, they primarily excite nitrogen, in turn causing the bright blue glow.

These blue blasts aren’t uncommon. They’ve been observed from both the ground and in aircraft, but their mechanism of action was largely a mystery. Now, readings from the ISS are helping scientists better understand these stratospheric cobalt crackles, according to Science News.

The Results Are Enlightening

Using both traditional cameras and light-sensing photometers, the ISS has observed a number of blue jet events. However, in 2019, the Atmosphere-Space Interactions Monitor on the ISS captured the emergence of blue jet lightning from a storm system near the island of Nauru in the Pacific Ocean, according to the results published in Nature.

“The photometer signal in the blue band increased more than two orders of magnitude in the span of 10-20 μs, suggesting that the emissions are from the cloud top, where photons reaching the instruments are relatively unaffected by scattering in the cloud,” the study says.

Torsten Neubert, an astrophysicist from the Technical University of Denmark in Kongens Lyngby, told Science News that the data collected suggests that these blue jets start with sparks that may be linked to short-range electric discharges within the clouds themselves. Instead of arcing from clouds to the ground like normal lighting, these blue bolts travel upward while cloud mixing at higher altitudes brings oppositely-charged areas much closer together (within a kilometer) to prompt quick but powerful bursts of energy. The ISS also caught sight of four accompanying ultraviolet Emissions of Light and Very Low-Frequency Perturbations due to Electromagnetic Pulse Sources — also known as ELVES, since the scientific term is quite a mouthful.

It’s also worth noting that Earth isn’t alone in experiencing these transient luminous events (TLEs). According to Forbes, similar flashes of powerful lightning have been observed above the clouds of Jupiter, though at a much greater magnitude.

Still, They’re a Little Bit Frightening

Blue jets and ultraviolet ELVES aren’t the only TLEs occurring in Earth’s atmosphere. Red sprites were first reported in 1886 and photographed in 1989. They’re tied to cold plasma discharges that occur above terrestrial lightning strikes and often resemble jellyfish, as Forbes points out. According to Smithsonian Magazine, these natural phenomena are much lower-energy than their blue jet counterparts and are rarely observable with the naked eye. Seeing them from Earth typically requires significant distance (100 miles or so), a lack of light pollution and a storm system that’s generating a significant amount of lightning.

While the risk of getting struck by a blue jet or stung by a red jellyfish sprite is far lower than the already minimal chance of Earthbound zaps from typical lightning, there’s still some cause for concern, especially when it comes to radio communication. As Eos notes, when thunderstorm updrafts strengthen, the resulting electrification of clouds can cause temperature increases in the lower ionosphere, which can lead to “prolonged disturbances to radio waves in the rarefied atmospheric layer.” Powerful blue jets could potentially precipitate the same issue at higher altitudes, in turn disrupting orbit-to-Earth or space-to-Earth communications for substantive periods of time.

The result? The more we know about the natural phenomena of blue jets — what causes them, how often they happen and where they’re likely to occur — the better for our atmospheric efforts.

Check out Northrop Grumman career opportunities to see how you can participate in this fascinating time of discovery in science, technology and engineering.

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