Linear lightning is well studied and has a clear scientific explanation. As you know, all of them are formed in the lower atmosphere at an altitude of 12-16 km. However, for a long time, airplane pilots received reports of short-term light phenomena in the upper atmosphere at an altitude of 30, 50 and even 100 km, where ordinary linear lightning cannot be. At first, scientists did not attach importance to such evidence, and the phenomena themselves were considered more mythical than real. But it was not possible to ignore them for a long time, since later the existence of the phenomenon was proved and even recorded in the photo. Several years ago, a Danish astronaut managed to photograph even one of the rarest such phenomena from the International Space Station. All of them are electrical discharges, that is, lightning, which is usually called high-altitude. Depending on their appearance, they were classified, highlighting several main types - jets, sprites, elves, etc. Moreover, scientists managed to find out the origin of some of them.
High-rise lightning - what are they and how they differ
Most often in the media, you can hear about red sprites, as they are the most common occurrence. They were first photographed in 2005. Scientists describe them as bright lumps, similar to ball lightning, which first fly downward with great speed and then rise vertically upward. Their speed is one tenth of the speed of light.
Sprites appear at an altitude of 50 km above sea level and above
There are also elves who are almost indistinguishable by the human eye. They are weak cone-shaped flares. But, the most mysterious lightning bolts are blue jets. It was this phenomenon that the Danish cosmonaut managed to record. Scientists learned about its existence relatively recently - only in 1995. The blue jet hits vertically upward, and its length can reach 60 km.
Blue jet - where does it come from
The blue jets are the closest to the lightning earth. They appear in the same place as ordinary linear ones, that is, in thunderclouds, only they are formed not at their lower boundary, but at their upper edge. The duration of such discharges is several tens of microseconds.
After the discharge, a short bright segment immediately appears, which, similarly to linear lightning, was called the leader. It happens that lightning ends with a simple flash of the leader, especially when it forms at a low altitude. But, most often, as noted by scientists, jets, or streamers, spread vertically upward from the streamer. They pervade the entire stratosphere.
Blue jets arise for the same reasons as linear lightning
To study these lightning strikes, special equipment was installed on the Columbus module of the International Space Station in 2018. It included optical cameras, photometers, as well as a high-sensitivity submillimeter spectrometer and detectors that record X-ray and gamma radiation. As a result, a year later, scientists managed to record blue jets that formed in a thundercloud over the Pacific Ocean.
The fixed jet has reached the stratopause - that is, the layer located on the border between the stratosphere and the mesosphere. It is located at an altitude of about 50 kilometers. The research results were published in the journal Nature. They say that blue jets appear due to electrical breakdown that occurs between the charge located at the top of the thundercloud and the layer of air above it, which has a negative discharge. That is, they arise as a result of the same processes that lead to the appearance of ordinary lightning. The blue color of the jets, according to scientists, is due to the ionization of nitrogen molecules.
Elf, sprite - lightning in the uppermost layers of the atmosphere
Even higher, at an altitude of 50 to 80 km, cold plasma discharges with a characteristic red color appear - these are the so-called sprites. They appear after a split second after a powerful lightning strike. As mentioned above, sprites propagate up and down. Since the material in them is not heated to ultra-high temperatures, they resemble cold flashes of plasma.
Elves appear at an altitude of about 100 km and from Earth resemble UFOs
As a rule, at the border of the mesosphere and ionosphere, they diverge in rings of red light hundreds of kilometers in diameter, which are called elves. They usually appear above powerful hurricanes at an altitude of about 100 km above sea level. Scientists speculate that elves glow as a result of the emission of excited nitrogen molecules. They are charged by electrons accelerated as a result of a thunderstorm.
In addition, there are many other poorly understood lightning strikes in the upper atmosphere. According to experts, they are all electrically induced types of glowing plasma. It is practically impossible to notice them from the Earth and even more so to study them, since during a thunderstorm they are hidden behind the clouds. Therefore, the first full-fledged information about them was obtained only from orbit.
Observations of jets, elves and other high-altitude lightning continue.