Daniel Tarr (et.al)
Transient Luminous Events
Sprites, Elves, Jets
2013.
Thunderstorms have always been treated with thunder and lightning, the people in fear and fascination: The ancient Greeks brought the flash in conjunction with Zeus, the most powerful of the gods. And although nowadays knows about the electrical nature of this natural phenomenon, it has not yet revealed all its secrets. For example, strange light phenomena have repeatedly been observed in the higher regions of the night sky, some could be explained as auroras or bizarre illuminated clouds, but others were puzzling. In particular, pilots observed in the darkness high above thunderstorm clouds occasionally spooky lights.
Most scientists took these reports seriously - to John R. Winckler and his team at the University of Minnesota in Minneapolis in 1990 for the first time one of the most puzzling phenomena with the video camera held fast. The images revealed flashes of a completely new type.
Now began active efforts to document such discharges in the upper envelope of air. Since then it has - from the space shuttle, aircraft and from the ground - seen hundreds of them. Thus it is clear that not only spectacular lightning flashes in the lowest layers of air between thunderclouds and the ground back and forth: Often there are discharges in the thin air layers up to 90 kilometers above the clouds.
In retrospect is amazing that you have not discovered this earlier events; actually should have been expected lightning-like luminous phenomena at the highest altitudes of the atmosphere almost. It has long been known that the ultraviolet radiation from the Sun ionizes the air molecules far beyond the turbulent layers of the atmosphere, ie knocks electrons out of them. In this way, about 80 kilometers above the ionosphere, an electrically conductive layer in hundreds of kilometers up gradually in the near-Earth space.
The phenomenon has been discovered at the beginning of aviation, but often dismissed as spinning of pilots. The result was that pilots concealed many such observations in the sequence.
Since these flashes are difficult to observe from the ground, there was a long few photographs of it until targeted recordings from 1989 - primarily from airplanes and space shuttles - have been made. |
Sprites on Film. See also: Mystery of the Red Sprites. |
As a leprechaun (of English. Sprite, spirit ',' puck ') is referred to in meteorology a flash that reaches an altitude of 100 kilometers, beats up during a thunderstorm above the clouds. Most goblins are columnar, sometimes they look like a mushroom cloud.
Leprechauns are about 100 - to 1000-times more intense than typical flashes and cover partly widths of up to 50 km and can be during discharge divided into several areas. Sprites occur in classic, more line-like structure like normal lightning flashes then particularly easy when a channel is pre-ionized air. Then barreled flashes can form also in higher layers. This was observed for example in the entry of meteors in its orbit to be attracted lightning. Also produce such missiles Ionisationsgebilde line like that go back several kilometers behind the rocket and promote strong flashes. For the first time in 1987 attracted public attention, such a case, when a rocket from NASA in achieving high layers of the atmosphere caused a fire, which destroyed their electronics and made it necessary to blow up the rocket.
In about 40 km altitude arise in a similar way blue cone-shaped discharge (blue jets) that can take tens of seconds and run up or down according to various sources, the first reports date back to 1989.
When the elves (English elves) is lightning discharges that illuminate the gases in the ionosphere. They occur over large storm clouds as a reddish ring at about 90 km altitude and are probably induced by cloud flashes.
Transient Luminous Events
Until recently, it was thought that the dazzling display of light offered by a thunderstorm was confined to the lightning activity in the thunderstorm clouds and between the clouds and the ground. This changed in 1989 with the first scientific documentation of a brilliant optical flash well above a thunderstorm [Franz et al., 1990], following years of intermittent but persistent verbal reports of such high-altitude flashes by pilots and others [Vaughan and Vonnegut, 1989, and references therein]. Publication of the photograph of the flash stoked a great amount of scientific interest in the subject of lightning-associated high-altitude (above cloud) flashes, and within a few years a menagerie of different kinds of flashes had been discovered. The different kinds of flashes were given fanciful names like "sprites" and "elves" to reflect their fleeting and hard-to-catch nature (and to steer clear of names suggesting causative mechanisms which had not yet been pinned down), and the entire category of flashes came to be known as transient luminous events (TLEs). Examples of various kinds of TLEs are shown in Figure 1.
Figure 1: Examples of various transient luminous events: (a) the first recorded sprite (from Figure 1 of Franz et al. [1990]), (b) the first color recording of a sprite (from Figure 1 of Sentman et al. [1995]), (c) the first recorded elve (from Figure 2 of Boeck et al. [1992], (d) one of the first recordings of a jet (from Figure 3 of Wescott et al. [1995]), (e) the first recording of a rare gigantic jet (from Figure 2 of Pasko et al. [2002]).
Sprites are large, brief, and often highly-structured bursts of light occurring high above thunderstorms in response to cloud-to-ground lightning flashes that remove large amounts of charge from the upper portions of a cloud. A single sprite can span altitudes from 40 km up to 80 km (the cloud itself is no higher than 15 km) with a width of several tens of kilometers at its widest. Often, the highest parts of a sprite feature a diffuse, red glow (called a halo) while the lower parts of a sprite feature highly structured streamers of a blue color, although halos can appear without streamers and streamers can appear without halos. Sprites last for several milliseconds to several tens of milliseconds, long enough to be barely perceptible to the human eye. The now-accepted theory of sprite formation was first put forth by the VLF Group [Pasko et al., 1996; Pasko et al., 1997; Pasko et al., 1995].
Elves are rapidly expanding rings of predominantly red light centered well above a causative cloud-to-ground lightning return stroke. Elves expand radially outward along the lower edge of the ionosphere (80-90 km) with an apparent speed faster than light and can attain diameters up to 300 km across (covering an area similar to the size of West Virginia) on timescales faster than 1 ms. The rapid timescales make elves too quick to see with the naked eye and difficult to catch on standard 30 fps video cameras, but use of specially-designed photometric imaging instruments have shown that elves are easily the most frequently occurring TLE on the planet (a recent 3-year satellite study observed around 600 sprites and over 5000 elves, with a globally averaged elve occurrence rate of over 3 elves/min) [Chen et al., 2008]. Large storms can produce hundreds of elves over the course of a few hours [Newsome and Inan, 2010]. Elves are an example of a natural phenomenon that was predicted to occur before it was actually first observed: the VLF Group first hypothesized the existence of elves in [Inan et al., 1991]. |
First color image of a sprite, taken from an aircraft. |
Jets are associated with upward-directed lightning shooting out of cloud tops and vary greatly in size. Blue in color, the smallest jets are called blue starters and extend only a few kilometers from the cloud top into the clear air above. Jets extend much further into the stratosphere, to altitudes around 40 km. Both starters and jets occur relatively frequently (around the same rate as sprites). Gigantic jets, which reach altitudes as high as 80 km, are on the other hand exceedingly rare. In the same 3-year study cited above where over 5000 elves and around 600 sprites were observed, only 13 gigantic jets were observed, predominantly over oceans [Chen et al., 2008].
The VLF Group and TLEs
The VLF Group has been deeply involved in TLE research since the subject's scientific inception in 1989, making numerous theoretical contributions and observational discoveries. Much of the VLF Group's work has been driven by in-the-field TLE observation campaigns carried out all over the world with novel imaging instrumentation developed and built at Stanford. Locations for these campaigns over the years have included the Rocky Mountain Front Range of Colorado (looking into the US Great Plains), the Magdalena Mountains of New Mexico, Arecibo Observatory in Puerto Rico, Pic du Midi in the French Pyrenees, Japan, and South Africa.
Figure 2: Photos from various TLE observation campaigns over the years: (lower left) Yucca Ridge Field Site near Ft. Collins, Colorado, (middle and lower right) Observatoire Midi-Pyrenees at the top of Pic du Midi in the French Pyrenees, (right side) South African Astronomical Observatory near Sutherland, South Africa, (top) Langmuir Laboratory at the top of South Baldy Peak in the Magdalena Mountains near Socorro, New Mexico
Novel approaches to TLE imaging and imaging instruments developed by the VLF Group include:
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The PIPER Instrument [ Marshall et al., 2008], a 64-anode two-dimensional photometric array imager capable of free-running (non-triggered) ground-based recording of aggregate elve activity over active thunderstorms [ Newsome and Inan, 2010]. PIPER was the first instrument to document hundreds of elves from a single storm system as well as observe an unusual class of elve (elve doublets, see Figure 3) in large numbers. PIPER has been deployed for TLE observation in New Mexico, Colorado, Puerto Rico, and France.
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The WASP (Wide-angle Array for Sprite Photometry), a two-row horizontal photometer array, used in numerous sprite observation campaigns, including the conjugate sprite observation campaign from South Africa [ Marshall et al., 2005].
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Figure 3: Observation of a rare elve doublet over West Texas as seen by the PIPER instrument from Langmuir Laboratory in New Mexico
Acknowledgements
Recent study of TLEs by the VLF Group has been funded by the Office of Naval Research (ONR). Portions of this material are based upon work supported by the National Science Foundation under Grant No. ATM-0836326. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
Bibliography
- Barrington-Leigh, C. P., and U. S. Inan, Elves triggered by positive and negative lightning discharges, Geophys. Res. Lett., 26(6), 683-686, 1999.
- Barrington-Leigh, C. P., U. S. Inan, and M. Stanley, Identification of sprites and elves with intensified video and broadband array photometry, J. Geophys. Res., 106(A2), 1741-1750, 2001.
- Boeck, W. L., O. H. Vaughan, R. Blakeslee, B. Vonnegut, and M. Brook, Lightning induced brightening in the airglow layer, Geophys. Res. Lett., 19(2), 99-102, 1992.
- Chen, A. B., et al., Global distributions and occurrence rates of transient luminous events, J. Geophys. Res., 113, A08306, doi: rm10.1029/2008JA013101, 2008.
Franz, R. C., R. J. Nemzek, and J. R. Winckler, Television image of a large upward electric discharge above a thunderstorm, Science, 249(4964), 48-51, 1990.
- Gerken, E. A., and U. S. Inan, A survey of streamer and diffuse glow dynamics observed in sprites using telescopic imagery, J. Geophys. Res., 107(A11), doi: rm10.1029/2002JA009248, 2002.
- Gerken, E. A., and U. S. Inan, Observations of decameter-scale morphologies in sprites, J. Atmos. Sol.-Terr. Phys., 65(5), 567-572, doi: rm10.1016/S1364-6826(02)00333-4, 2003.
- Gerken, E. A., U. S. Inan, and C. P. Barrington-Leigh, Telescopic imaging of sprites, Geophys. Res. Lett., 27(17), 2637-2640, 2000.
- Inan, U. S., T. F. Bell, and J. V. Rodriguez, Heating and ionization of the lower ionosphere by lightning, Geophys. Res. Lett., 18(4), 705-708, 1991.
- Inan, U. S., C. Barrington-Leigh, S. Hansen, V. S. Glukhov, T. F. Bell, and R. Rairden, Rapid lateral expansion of optical luminosity in lightning-induced ionospheric flashes referred to as 'elves', Geophys. Res. Lett., 24(5), 583-586, 1997.
- Marshall, R., R. Newsome, and U. Inan, Fast photometric imaging using orthogonal linear arrays, IEEE Trans. Geosci. Remote Sens., 46(11), 3885-3893, doi: rm10.1109/TGRS.2008.2000824, 2008.
- Marshall, R. A., and U. S. Inan, High-speed telescopic imaging of sprites, Geophys. Res. Lett., 32, L05804, doi: rm10.1029/2004GL021988, 2005.
- Marshall, R. A., and U. S. Inan, High-speed measurements of small-scale features in sprites: Sizes and lifetimes, Radio Sci., 41, RS6S43, doi: rm10.1029/2005RS003353, 2006.
- Marshall, R. A., U. S. Inan, T. Neubert, A. Hughes, G. Satori, J. Bor, A. Collier, and T. H. Allin, Optical observations geomagnetically conjugate to sprite-producing lightning discharges, Ann. Geophys., 23, 2231-2237, doi: rm10.5194/angeo-23-2231-2005, 2005.
- Newsome, R. T., and U. S. Inan, Free-running ground-based photometric array imaging of transient luminous events, J. Geophys. Res., A00E41, doi: rm10.1029/2009JA014834, 2010.
- Pasko, V. P., U. S. Inan, Y. N. Taranenko, and T. F. Bell, Heating, ionization and upward discharges in the mesosphere due to intense quasi-electrostatic thundercloud fields, Geophys. Res. Lett., 22(4), 365-368, 1995.
- Pasko, V. P., U. S. Inan, and T. F. Bell, Blue jets produced by quasi-electrostatic pre-discharge thundercloud fields, Geophys. Res. Lett., 23(3), 301-304, 1996.
- Pasko, V. P., U. S. Inan, T. F. Bell, and Y. N. Taranenko, Sprites produced by quasi-electrostatic heating and ionization in the lower ionosphere, J. Geophys. Res., 102(A3), 4529-4561, 1997.
- Pasko, V. P., M. A. Stanley, J. D. Mathews, U. S. Inan, and T. G. Wood, Electrical discharge from a thundercloud top to the lower ionosphere, Nature, 416, 152-154, 2002.
- Sentman, D. D., E. M. Wescott, D. L. Osborne, D. L. Hampton, and M. J. Heavner, Preliminary results from the sprites94 aircraft campaign: 1. red sprites, Geophys. Res. Lett., 22(10), 1205-1208, 1995.
- Vaughan, O. H., and B. Vonnegut, Recent observations of lightning discharges from the top of a thundercloud into the clear air above, J. Geophys. Res., 94(D11), 13,179-12,182, 1989.
- Wescott, E. M., D. Sentman, D. Osborne, D. Hampton, and M. Heavner, Preliminary results from the sprites94 aircraft campaign: 2. blue jets, Geophys. Res. Lett., 22(10), 1209-1212, 1995.
[ Source : Stanford VLF Group ]
Sprites
Sprites are large-scale electrical discharges that occur high above thunderstorm clouds, or cumulonimbus, giving rise to a quite varied range of visual shapes flickering in the night sky. They are triggered by the discharges of positive lightning between an underlying thundercloud and the ground.
The phenomena were named after the mischievous sprite (air spirit) Puck in William Shakespeare's A Midsummer Night's Dream. They normally are colored reddish-orange or greenish-blue, with hanging tendrils below and arcing branches above. They can also be preceded by a reddish halo. They often occur in clusters, lying 50 kilometres (31 mi) to 90 kilometres (56 mi) above the Earth's surface. Sprites have since been witnessed tens of thousands of times. Sprites have been held responsible for otherwise unexplained accidents involving high altitude vehicular operations above thunderstorms.
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Sprites appear as luminous reddish-orange flashes. They often occur in clusters within the altitude range 50–90 km (31–56 mi) above the Earth's surface. Sporadic visual reports of sprites go back at least to 1886, but they were first photographed on July 6, 1989 by scientists from the University of Minnesota and have subsequently been captured in video recordings many thousands of times.
Sprites are sometimes inaccurately called upper-atmospheric lightning. However, sprites are cold plasma phenomena that lack the hot channel temperatures of tropospheric lightning, so they are more akin to fluorescent tube discharges than to lightning discharges.
Allusions to transient optical phenomena above thunderclouds can be found in anecdotal reports from as early as 1730 (see Johann Georg Estor). Nobel laureate C. T. R. Wilson had suggested in 1925, on theoretical grounds, that electrical breakdown could occur in the upper atmosphere, and in 1956 witnessed what possibly could have been a sprite. They were first documented photographically on July 6, 1989 when scientists from the University of Minnesota, using a low-light video camera, accidentally captured the first image of what would subsequently become known as a sprite.
Several years after their discovery they were named » Sprites (air spirits) after their elusive nature. Since their 1989 discovery, sprites have been imaged tens of thousands of times, from the ground, from aircraft and from space, and have become the subject of intensive investigations. |
Sprite Characteristics
Sprites have been observed over North America, Central America, South America, Europe, Southern Africa (Zaire), Australia, the Sea of Japan and Asia and are believed to occur during most large thunderstorm systems.
Three types of sprites have been categorized by Matthew 'Geoff' McHarg Ph.D. (U.AK) of the US AirForce Research Academy (and NASA). Using an image intensifier on the front of super slow motion camera McHarg and his researchers have named the sprites based on their visual appearance.
- Jellyfish sprite - very large, up to 30 miles (48 km) by 30 miles (48 km).
- Carrot sprite
- C or Column sprite. These are large scale electrical discharges above the earth that are still not totally understood.
Sprites are colored reddish-orange in their upper regions, with bluish hanging tendrils below, and can be preceded by a reddish halo. They last longer than normal lower stratospheric discharges, which last typically a few milliseconds, and are triggered by the discharges of positive lightning between the thundercloud and the ground. They often occur in clusters of two or more, and typically span the altitude range 50 kilometres (31 mi) to 90 kilometres (56 mi), with what appear to be tendrils hanging below, and branches reaching above.
Optical imaging using a 10,000 frame-per-second high speed camera shows that sprites are actually clusters of small, decameter-sized (10–100 m, 30–300 ft) balls of ionization that are launched at an altitude of about 80 km (50 mi) and then move downward at speeds of up to ten percent the speed of light, followed a few milliseconds later by a separate set of upward moving balls of ionization. Sprites may be horizontally displaced by up to 50 km (31 mi) from the location of the underlying lightning strike, with a time delay following the lightning that is typically a few milliseconds, but on rare occasions may be up to 100 milliseconds.
In order to film sprites from Earth, special conditions must be present: 150–500 km (93–310 mi) of clear view to a powerful thunderstorm with positive lightning between cloud and ground, red-sensitive recording equipment, and a black unlit sky.
Sprites are sometimes preceded, by about 1 millisecond, by a sprite halo, a pancake-shaped region of weak, transient optical emissions approximately 50 kilometres (31 mi) across and 10 kilometres (6.2 mi) thick. The halo is centered at about 70 kilometres (43 mi) altitude above the initiating lightning strike. These halos are thought to be produced by the same physical process that produces sprites, but for which the ionization is too weak to cross the threshold required for streamer formation. They are sometimes mistaken for ELVES, due to their visual similarity and short duration. |
A sprite over Malaysia, as seen from the ISS. |
Recent research carried out at the University of Houston in 2002 indicates that some normal (negative) lightning discharges produce a sprite halo, and that every lightning bolt between cloud and ground attempts to produce a sprite or a sprite halo. Research in 2004 by scientists from Tohoku University found that very low frequency emissions occur at the same time as the sprite, indicating that a discharge within the cloud may generate the sprites.
Sprites have been blamed for otherwise unexplained accidents involving high altitude vehicular operations above thunderstorms. One example of this is the malfunction of a NASA stratosphericballoon launched on June 6, 1989 from Palestine, Texas. The balloon suffered an uncommanded payload release while flying at 120,000 feet (37,000 m) over a thunderstorm near Graham, Texas. Months after the accident, an investigation concluded that a "bolt of lightning" traveling upward from the clouds provoked the incident. The attribution of the accident to a sprite was made retroactively, since this term was not coined until late 1993.
[ Source : Wikipedia: Sprite ]
Spectacular Sprites
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This footage from the ISS shows
a "red sprite" over East Asia at around 0:06. |
In the blink of an eye, an enormous bright red light flashes above a thundercloud, spreading energetic branches that extend five times taller than Mount Everest and look like jellyfish tendrils and angel's wings.
These mysterious phenomena are known as Transient Luminous Events (TLEs), and are usually invisible to the naked eye because they happen on millisecond timescales, too fast to be seen. They occur between 50 to 100 kilometers above the ground, a long-ignored area of the atmosphere that is too high for aircraft but too low for satellites to investigate. There, the thin air interacts with strong electrical fields to ionize molecules and create arcing plasmas.
These spectacles are relatively new to science. Pilots had reported enigmatic bright flashes throughout the 20th century, but their anecdotal evidence didn't amount to proof. The first image of a TLE was captured accidentally in 1989 when a University of Minnesota professor aimed a low-light TV camera at the sky to film a rocket launch. Replaying the tape later on, Professor John R.
Winckler saw brilliant columns of light extending from the tops of storm clouds. Hearing of the finding, NASA officials immediately ordered a review of video tapes taken from the space shuttle that looked at lightning events on Earth. They found dozens more examples of TLEs, and later scientists have been recording them ever since.
"One of the neatest things about TLEs is that first image in 1989 was just a serendipitous capture," said amateur radio astronomer Thomas Ashcraft, who has been photographing the events for several years. |
Using a relatively simple camera and radio dish, Ashcraft has seen a whole bestiary of odd TLE phenomena. The most common are sprites, tall and highly structured bursts of light that appear above thunderstorms. They ionize the nitrogen in our atmosphere, causing a red glow. Often, they happen in conjunction with “Emissions of Light and Very Low Frequency Perturbations due to Electromagnetic Pulse Sources,” also known as ELVES, which are enormous halos of light that shoot outward to cover up to 500 kilometers in a millisecond. Though they are too short-lived to see, ELVES can produce bright afterglows that some people have mistaken for UFOs. Other TLEs have names like blue jets and trolls.
To deliver great TLE shots, Ashcraft first checks radar maps of the local area around his observatory in Santa Fe, New Mexico. Red spots on such maps indicate strong lightning cells, which increases the probability of sprite activity. Because the phenomena are mostly visible in near infrared wavelengths, he uses a modified off-the-shelf DLSR camera from which he removed the clear glass filter covering the CCD that blocks infrared light.
By taking continuous three-second exposures, Ashcraft records thousands of pictures each night. He then goes through the catalog looking for a sprite to appear. If he spots something, he can check a video camera that he has running during the night to see if captured more detail there. He shares his most interesting findings with other sprite observers, who may chime in with their own pictures from other positions.
From Santa Fe, Ashcraft says he can usually catch sprites up to 1,000 kilometers away. “I can see big storms out over the Great Plains, usually beyond Oklahoma City and into Nebraska,” he said. “After that, the curvature of the Earth gets in the way.”
Using a radio dish, Ashcraft also captures extremely low frequency emissions that the TLEs give off. He converts these into sound files, which can be heard in his videos, and can help researchers pick out details they might otherwise miss.
A lot of research regarding TLEs is still cutting-edge science, said Ashcraft. Only in recent years have scientists aimed high-speed cameras capable of capturing thousands of frames per second to study the spectacles in detail. While researchers had originally hypothesized that the phenomena were starting at the tops of thunderclouds, fast-motion videos prove that TLEs start as luminous spheres and then shoot upwards and downwards at the same time.
In this gallery, we take a look at some of Ashcraft’s most spectacular TLE recordings to get a better appreciation of these weird and wonderful phenomena.
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Different types of electrical phenomena in the atmosphere |
[ Source : Wired Science ]
Elves (TLEs)
ELVES often appear as a dim, flattened, expanding glow around 400 km (250 mi) in diameter that lasts for, typically, just one millisecond. They occur in the ionosphere 100 km (62 mi) above the ground over thunderstorms. Their color was a puzzle for some time, but is now believed to be a red hue. ELVES were first recorded on another shuttle mission, this time recorded off French Guiana on October 7, 1990. That ELVE was discovered in the Shuttle Video by the Mesoscale Lightning Experiment (MLE) team at Marshall Space Flight Center, AL led by the Principal Investigator, Otha H."Skeet" Vaughan, Jr.
ELVES is a whimsical acronym for Emissions of Light and Very Low Frequency Perturbations due to Electromagnetic Pulse Sources. This refers to the process by which the light is generated; the excitation of nitrogen molecules due to electron collisions (the electrons possibly having been energized by the electromagnetic pulse caused by a discharge from an underlying thunderstorm).
[ Source : Wikipedia: Upper-atmospheric lightning - Elves ]
Jets (TLEs)
Blue jets
Blue jets differ from sprites in that they project from the top of the cumulonimbus above a thunderstorm, typically in a narrow cone, to the lowest levels of the ionosphere 40 to 50 km (25 to 30 miles) above the earth. In addition, whereas red sprites tend to be associated with significant lightning strikes, blue jets do not appear to be directly triggered by lightning (they do, however, appear to relate to strong hail activity in thunderstorms). They are also brighter than sprites and, as implied by their name, are blue in color. The color is believed to be due to a set of blue and near-ultraviolet emission lines from neutral and ionized molecular nitrogen. They were first recorded on October 21, 1989, on a monochrome video of a thunderstorm on the horizon taken from the Space Shuttle as it passed over Australia. Blue jets occur much less frequently than sprites. By 2007, fewer than a hundred images had been obtained. The majority of these images, which include the first color imagery, are associated with a single thunderstorm. These were taken in a series of 1994 aircraft flights to study sprites.
Blue starters
Blue starters were discovered on video from a night time research flight around thunderstorms and appear to be "an upward moving luminous phenomenon closely related to blue jets." They appear to be shorter and brighter than blue jets, reaching altitudes of only up to 20 km. "Blue starters appear to be blue jets that never quite make it," according to Dr. Victor P. Pasko, associate professor of electrical engineering.
Gigantic jets
On September 14, 2001, scientists at the Arecibo Observatory photographed a gigantic jet—double the height of those previously observed—reaching around 70 km (43 mi) into the atmosphere. The jet was located above a thunderstorm over an ocean, and lasted under a second. The jet was initially observed to be traveling up at around 50,000 m/s at a speed similar to typical lightning, increased to 160,000 and then 270,000 m/s, but then split in two and sped upward with speeds of at least 2,000,000 m/s to the ionosphere whence they spread out in a bright burst of light.
On July 22, 2002, five gigantic jets between 60 and 70 km (35 to 45 miles) in length were observed over the South China Sea from Taiwan, reported in Nature. The jets lasted under a second, with shapes likened by the researchers to giant trees and carrots.
On November 10, 2012, the Chinese Science Bulletin reported a gigantic jet event observed over a thunderstorm in mainland China on August 12, 2010. "GJ event that was clearly recorded in eastern China (storm center located at 35.6°N,119.8°E, near the Huanghai Sea)" |
Classic Blue Jet captured by Victor Pasko |
[ Source : Wikipedia: Upper-atmospheric lightning - Jets ]
Terrestrial Gamma-ray Flashes (TGFs)
This phenomenon is called Terrestrial Gamma-ray Flashes, or TGFs, and was perhaps the most surprising discovery of the Compton Gamma Ray Observatory beginning of the 1990s: if during the BATSE detector on the NASA satellite actually capture cosmic gamma-ray bursts from the depths of space ( and did so with flying colors), but he recorded during his nine-year measurements occasionally similar radiation that originated in the Earth's atmosphere. These TGFs lasted more than 3 milliseconds: Soon, it was demonstrated that each TGF was related to a particular lightning bolt, but only a tiny fraction of the lightning led to a detectable TGF.
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Satellite explore gamma-ray bursts of earthly thunderstorms |
Another surprising aspect of underground storm: The fraction was visible sprites could stand high above the clouds with just as short-lived terrestrial gamma-ray flash blocks. And the former phenomenon - here's a video still image of 1995 - even amateur astronomers everywhere with light-sensitive cameras. [Lockheed Palo Alto Research Laboratories]
That did not change even when the satellite RHESSI later registered 800 of the terrestrial gamma-ray flashes, while millions of thunderstorm lightning could "see" can in principle. The new gamma NASA satellites and Italy, Fermi and AGILE have already registered several TGFs, the data from Fermi - can register now seven times more than before thanks to a TGFs software change - even brought a new surprise. As a mechanism of generation of gamma radiation at TGFs were until then by electric fields accelerate electrons to nearly the speed of light, which collide with atoms of the atmosphere and emit bremsstrahlung. But the gamma radiation from some Fermi TGFs had exactly the energy decaying positrons, so of antimatter, which actually has nothing to look for in a thunderstorm with 511 keV. Maybe sometimes there is a cascade of collisions with positrons as a byproduct. AGILE has in turn can show that the energy of TGFs is up to tens of mega-electron volts, which is above the energy of known thunderstorm processes hundreds of times.
Thus, the TGF-phenomenon of interest as radiation process of the earth's most energy at all, even for aviation: A gamma-ray burst in the vicinity of an aircraft could be a significant radiation exposure to passengers, equivalent to 400 radiographs. You might have heard yes but to each flash and a TGF, which perhaps: the start of a mini-satellite called Firefly planned to be first look down specifically - to go to the mysterious flashes finally systematically to the bottom, is now even - in 2010 or 2011 even initiating the lightning discharge plays a role. |
[ Source : Allen Roswell ]
Light pillars
Columns of light apparently beaming directly upwards from unshielded (and wastefully polluting) lights are sometimes visible during very cold weather. Plate shaped ice crystals, normally only present in high clouds, float in the air close to the ground and their horizontal facets reflect light back downwards.
The pillars are not physically over the lights or anywhere else in space for that matter ~ like all halos they are purely the collected light beams from all the millions of crystals which just happen to be reflecting light towards your eyes or camera.
Artificial light pillars can be much taller than their natural counterparts because rays from the lights are not parallel and plate crystals with small tilts can still reflect them downwards. The crystals producing the pillars are roughly halfway between you and the lights.
When ice crystals float in the air around you, pillars (and other halos) can even be seen around streetlights a few metres away.
[ Source : Atmospheric Optics ]
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