"Sprite", "elves", "blue streams" - such strange semi-mystical names scientists have dubbed the rarest atmospheric phenomena on our planet. Mysterious plasma glow living in thousandths of a second and extending for hundreds of kilometers. It is almost impossible to see these atmospheric ghosts: they are so rare and impetuous. Their world is so high above the ground that it borders on the near space, and nature is not fully understood. But they are quite real and truly beautiful.
So strange, so familiar
For centuries, people have noticed mysterious lights high in the sky - beautiful, almost divine, sometimes creepy and frightening. In the old days, they were equated with the intrigues of evil spirits or with the divine edification of mortal
little human, which is why venerable scientists did not want to waste time on superstitious nonsense and simply ignored them. Only in the second half of the 20th century did scientists become really interested in them.
Pilots and cosmonauts sometimes observed certain substances, similar to rays, beating into space, balls, fountains and scattering rings of light, but the rarity and transience of such phenomena became an insurmountable obstacle to studying their nature. They were often mistaken for UFOs. For the first time, one of the phenomena (presumably it was sprites) was recorded only in 1989, and then by accident. On July 6, physicists from the University of Minnesota (USA) tested new equipment - a highly sensitive camera for studying the starry sky. By pure chance, strange funnel-shaped flares generated by a distant thunderstorm hit the lens. They lasted only milliseconds, but the scale of the phenomena unknown to science shocked the imagination - each flash extended at least 30 km. Those moments were the beginning of a large-scale hunt for heavenly ghosts.
The first clear images of atmospheric fires were obtained only a decade and a half later - in 2005 - using a special camera with a shooting speed of 5000 frames per second. With the accumulation of factual material, it became clear that the glow is not of the same type, they can be classified. So scientists discovered jellyfish-shaped balls "sprites", reminiscent of bluish rays "blue jets (jets)", red fountains "tigers" and ephemeral rings of "elves".
A prerequisite for the occurrence of atmospheric fires is severe thunderstorms. Most of them are observed in the mesosphere at an altitude of 50-130 km, while ordinary lightning almost never "picks up" above 16 km. Not to mention the fact that the high-altitude plasma glow is truly enormous. Living for a fraction of a second, they can grow up to hundreds of kilometers - tens of times longer than linear lightning. They are amazing, if only because they cannot be ranked as lightning or auroras. These are phenomena of a completely different nature.
Promotional video:
Let's turn to the terminology. What is lightning? It is a high energy spark discharge, hot and destructive. The aurora is a low-energy glow of the upper layers of the atmosphere that occurs when the Earth's magnetosphere interacts with particles of the solar wind, a stream of charged particles emitted by the Sun.
Ordinary lightning can easily kill a person, but the aurora can harm only by the accompanying cosmic radiation, from which the inhabitants of the Earth are safely protected by the magnetic field that surrounds our planet like a shield. The phenomena under consideration are fundamentally different. Roughly speaking, atmospheric lights are referred to as high-altitude lightning, although in reality they are not. The difference between the two is the same as between the decorative plasma lamp and the arc of a welding machine. They, like auroras, are cold plasma discharges. But unlike Aurora Borealis (northern lights), they can be observed anywhere in the world, and they do not arise under the influence of rays from the outside - they are generated by the planet itself.
"It is generally accepted that the weather we see every day and the processes in the upper atmosphere exist on their own," says NASA employee Karen Fox. “The existence of high-altitude lightning proves that both near-Earth spheres are interconnected, and it remains to be seen how energy is exchanged between them.”
Sprites
Historically, sprites became the first birds of the future galaxy of atmospheric plasma glow. Sprites (from the English sprite - "fairy") are colossal spherical streams of ionized plasma that arise over thunderstorm fronts and directed vertically upward. Outwardly, they look like flashes of red-orange or blue radiance, dividing into a "body", numerous lower "branches" and short "candles" directed upwards. Because of this, they are sometimes compared to jellyfish, which scattered their graceful tentacles across the sky. Red sprites, devoid of a ball-shaped thickening, are sometimes called "tigers", but this is not entirely true. Tigers usually appear at lower altitudes, differ in luminosity and have a different external structure.
Sprites usually appear in groups, forming ring clusters, and make "dancing" movements up and down, which is why they were named after fairies - playful luminous creatures who, according to old legends, loved to gather in glades and dance, arranging a difficult round dance.
From the ground, sprites usually appear as small colored lights in the sky, but in reality they are huge. The height and range at which it becomes possible to observe the lights distorts the real scale of their greatness. Even the most modest sprite is 60 km long and 100 km in diameter.
Until recently, the study of plasma jellyfish was possible only with the help of cameras on the top of the mountains, but the data obtained were scarce and unreliable. Today, the necessary equipment is located on the ISS, which allows observing huge flares escaping from the clouds without interference. With the help of ASIM (Atmospheric Space Interaction Monitor), the European Space Agency hopes to find patterns in the frequency of occurrence of sprites and finally understand their nature.
Elves
Often elves become companions of sprites in the sky. Do not be fooled by this name, it was invented many years after the world stopped believing in miracles. "Elf" is a free transcription of ELVES, Emission of Light and Very Low Frequency perturbations due to Electromagnetic Pulse Sources, which literally means "emission of light and very low frequency disturbances due to a pulse from an electromagnetic source." These are the modern fairy tales.
Ionospheric elves are radiating reddish rings that spread like the edge of a shock wave. They appear around sprites and especially powerful storms at altitudes exceeding 100 km. Their lives are fleeting - only a few milliseconds.
Scientists believe that the mechanism of their glow is associated with the radiation of excited nitrogen molecules, which receive energy from electrons accelerated due to discharges in the underlying storm. What connects them with sprites and whether there is any pattern for their coexistence is still unclear.
Blue jets
Another phenomenon is blue jets. They also form when electrons are pulled out of thunderclouds, but unlike sprites, which require a slow, slow current, jets need a more powerful directional impulse. Of all the plasma effects, blue jets form the lowest, directly above the storm clouds. Born in active storm centers, the jets rise to a height of 40-50 km at a speed of about 100 km / s, where they begin to gradually dissipate and fade. They "live" longer than sprites, but they are also observed less often, which significantly complicates their study. It is not known for certain whether they are a form of high-altitude lightning or plasma mesospheric phenomena. Scientists tend to favor the latter, but evidence for this remains to be found.
Steves
Knowledge about atmospheric fires is still extremely scarce. Another proof of this is the recent discovery of a new type of radiation. In 2017, Chris Ratzlaff, a member of the amateur auroral research group Alberta Aurora Chasers, observed atypical light streaks in the night sky. Chris and his associates believed that this effect was caused by a positively charged aurora, and called it "proton arcs." When the photographs of amateurs fell into the hands of professor of physics at the University of Calgary (Canada) Eric Donovan, it turned out that behind an unremarkable at first glance a stroke against the background of the stars was a phenomenon unknown to science. Using data from the Swarm satellite, Donovan found that the glow was caused by a 25-kilometer ribbon of gas heated to 3000 ° C, located at an altitude of 300 km and moving at a speed of 6 km / s. Unlike its fast-moving counterparts, it can last more than an hour and is seasonal in nature, appearing mainly from March to September. The discovery was named "Steve" from the abbreviation Strong Thermal Emission Velocity Enhancement (from English. "High-temperature accelerating radiation"). More precisely, the opposite. The dry scientific abbreviation was later artificially adjusted to the original name given to the phenomenon by the discoverer. Ratzlaff christened the glow Steve as a joke, quoting from the cartoon "The Woodsmen", where the heroes encounter something unknown and decide to name it "Steve". More precisely, the opposite. The dry scientific abbreviation was later artificially adjusted to the original name given to the phenomenon by the discoverer. Ratzlaff christened the glow Steve as a joke, quoting from the cartoon "The Woodsmen", where the heroes encounter something unknown and decide to name it "Steve". More precisely, the opposite. The dry scientific abbreviation was later artificially adjusted to the original name given to the phenomenon by the discoverer. Ratzlaff christened the glow Steve as a joke, quoting from the cartoon "The Woodsmen", where the heroes encounter something unknown and decide to name it "Steve".
The very existence of these seemingly simple fleeting ghosts can change the science's understanding of the atmosphere and electromagnetic phenomena of our planet. The earth is not just a magnetized piece of rock covered with a layer of gas mixture. It is practically a living organism, a world of complex fundamental interactions lasting a fraction of a moment, but existing for billions of years. Even with the current level of technology development, scientists have learned very little about plasma atmospheric glow. Almost nothing. Right now, amazing phenomena are taking place over our heads, proving that if something seems “too simple”, then we still don't understand anything about it.
Magazine: Secrets of the Universe №2 (147). Author: Kirill Rogachev