Blue Jet
Scientists have finally gotten a clear view of the spark that sets off an exotic type of lightning the blue jet.
Blue planes zip upward from storm clouds into the stratosphere, arriving at elevations up to around 50 kilometers in under a second. Though standard lightning energizes a variety of gases in the lower environment to gleam white, blue planes energize generally stratospheric nitrogen to make their particular blue tone.
Understanding blue jets and other upper-atmosphere phenomena related to thunderstorms, such as sprites (SN: 6/14/02) and elves (SN: 12/23/95), is important because these events can affect how radio waves travel through the air — potentially impacting communication technologies, says Penn State-space physicist Victor Pasko, who was not involved in the work.
Instruments on the International Space Station have spotted a blue jet emerges from an extremely brief, bright burst of electricity near the top of a thundercloud, researchers report online January 20 in Nature. Blue jets have been observed from the ground and aircraft for years, but it’s difficult to tell how they form without getting high above the clouds.
Cameras and light-detecting instruments called photometers on the space station noticed the blue fly in a tempest over the Pacific Ocean, close to the island of Nauru, in February 2019. “The entire thing begins with my opinion about as a blue blast,” says Torsten Neubert, an air physicist at the Technical University of Denmark in Kongens Lyngby. That “blue blast” was a 10-microsecond blaze of brilliant blue light close to the highest point of the cloud, around 16 kilometers high. From that flashpoint, a blue stream shot up into the stratosphere, moving as high as around 52 kilometers more than a few hundred milliseconds.
The sparkle that produced the blue stream may have been a unique sort of short-range electric release inside the storm cloud, Neubert says. Ordinary lightning jolts are framed by releases between oppositely charged areas of a cloud — or a cloud and the ground — numerous kilometers separated. In any case, violent blending high in a cloud may bring oppositely charged locales inside about a kilometer of one another, making short yet amazing eruptions of electric flow, Neubert says. Scientists have seen proof of such high-energy, short-range releases in beats of radio waves from tempests identified by ground-based receiving wires.
