Upper-atmospheric lightning
Encyclopedia
Lightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
and storm clouds. Upper-atmospheric lightning is believed to be electrically induced forms of optical fluorescence
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...
. The preferred usage is transient luminous event, because the various types of electrical-discharge phenomena in the upper atmosphere lack several characteristics of the more familiar tropospheric lightning. TLEs include red sprites, sprite halos, blue jets, gigantic jets, and elves.
Characteristics
There are several types of TLEs, the most common being spritesSprite (lightning)
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...
. Sprites are flashes of bright red light that occur above storm
Storm
A storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface, and strongly implying severe weather...
systems. C-sprites (short for "columniform sprites") is the name given to vertical columns of red light. C-sprites exhibiting tendrils are sometimes called carrot sprites. Other types of TLEs include gnomes, blue jets, gigantic jets, blue starters, and elves, the latter being the plural of "ELVE," a somewhat forced acronym for "e(mission of) l(ight and) v(ery low-frequency perturbations from) e(lectromagnetic pulse sources)". TLEs are secondary phenomena that occur in the upper atmosphere in association with underlying thunderstorm
Thunderstorm
A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...
lightning
Lightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
.
TLEs generally last anywhere from less than a millisecond to more than 2 seconds. The first TLE was captured accidentally in a video recording in 1989. University of Minnesota
University of Minnesota
The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 52,557...
researchers were waiting to record a rocket launch
Rocket launch
A rocket launch is the takeoff phase of the flight of a rocket. Launches for orbital spaceflights, or launches into interplanetary space, are usually from a fixed location on the ground, but may also be from a floating platform such as the San Marco platform, or the Sea Launch launch...
and pointed the camera at a distant thunderstorm. A TLE was later identified, appearing in only two frames of the film. TLEs have been captured by a variety of optical recording
Optical recording
The history of optical recording can be divided into a few number of distinct major contributions. The pioneers of optical recording worked mostly independently, and their solutions to themany technical challenges have very distinctive features, such as...
systems, with the total number of recorded events currently (early 2009) estimated at many tens-of-thousands. The global rate of TLE occurrence has been estimated from satellite (FORMOSAT-2
FORMOSAT-2
FORMOSAT-2 is an Earth observation satellite operated by the National Space Organization of the Republic of China . It is a high-resolution photographic surveillance satellite with a daily revisit capability. Images are commercially available from Spot Image.- Launch :FORMOSAT-2 was launched...
) observations to be several million events per year.
History
In the 1920s, the Scottish physicist C.T.R. WilsonCharles Thomson Rees Wilson
Charles Thomson Rees Wilson, CH, FRS was a Scottish physicist and meteorologist who received the Nobel Prize in physics for his invention of the cloud chamber.- Biography:...
predicted that electrical breakdown should occur in the atmosphere high above large thunderstorms. In ensuing decades, high altitude electrical discharges were reported by aircraft pilots and discounted by meteorologists until the first direct visual evidence was documented on July 6, 1989 by scientists from the University of Minnesota
University of Minnesota
The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 52,557...
. Several years later, the optical signatures of these events were named 'sprites' by researchers at the University of Alaska to avoid inadvertently implying physical properties that were, at the time, still unknown. The terms red sprites and blue jets gained popularity after a video clip was circulated following an aircraft research campaign to study sprites in 1994.
Sprites
Thunderstorm
A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...
cloud, or cumulonimbus, giving rise to a quite varied range of visual shapes. They are triggered by the discharges of positive lightning between the thundercloud and the ground. The phenomena were named after the mischievous sprite (air spirit) Puck in William Shakespeare
William Shakespeare
William Shakespeare was an English poet and playwright, widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's national poet and the "Bard of Avon"...
's A Midsummer Night's Dream
A Midsummer Night's Dream
A Midsummer Night's Dream is a play that was written by William Shakespeare. It is believed to have been written between 1590 and 1596. It portrays the events surrounding the marriage of the Duke of Athens, Theseus, and the Queen of the Amazons, Hippolyta...
. 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 (31.1 mi) to 90 kilometres (55.9 mi) above the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
's surface. Sprites were first photographed on July 6, 1989 by scientists from the University of Minnesota
University of Minnesota
The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 52,557...
and 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.
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 ionosphereIonosphere
The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...
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
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
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 studied by researchers from the University of Alaska. 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 ObservatoryArecibo Observatory
The Arecibo Observatory is a radio telescope near the city of Arecibo in Puerto Rico. It is operated by SRI International under cooperative agreement with the National Science Foundation...
photographed a gigantic jet—double the height of those previously observed—reaching around 70 km (43.5 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 in a way similar to a typical blue jet but then split in two and sped at 250,000 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
South China Sea
The South China Sea is a marginal sea that is part of the Pacific Ocean, encompassing an area from the Singapore and Malacca Straits to the Strait of Taiwan of around...
from Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, reported in Nature. The jets lasted under a second, with shapes likened by the researchers to giant trees and carrots.
Elves
Elves often appear as a dim, flattened, expanding glow around 400 km (248.5 mi) in diameter that lasts for, typically, just one millisecond. They occur in the ionosphere 100 km (62.1 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 GuianaFrench Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...
on October 7, 1990.
Elves is a whimsical acronym for Emissions of Light and Very Low Frequency Perturbations from Electromagnetic Pulse Sources. This refers to the process by which the light is generated; the excitation of nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
molecules due to electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
collisions (the electrons possibly having been energized by the electromagnetic pulse caused by a discharge from an underlying thunderstorm).
See also
- St. Elmo's fireSt. Elmo's fireSt. Elmo's fire is a weather phenomenon in which luminous plasma is created by a coronal discharge from a grounded object in an electric field in the atmosphere St. Elmo's fire is named after St. Erasmus of Formiae St. Elmo's fire (also St. Elmo's light) is a weather phenomenon in which luminous...
- Aurora (astronomy)Aurora (astronomy)An aurora is a natural light display in the sky particularly in the high latitude regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere...
- Sprite (lightning)Sprite (lightning)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...
- Schumann resonances
External links
- Homepage of the Eurosprite campaign, itself part of the CAL (Coupled Atmospheric Layers) research group
- March 2, 1999, University of Houston: UH Physicists Pursue Lightning-Like Mysteries Quote: "...Red sprites and blue jets are brief but powerful lightning-like flashes that appear at altitudes of 40-100 km (25-60 miles) above thunderstorms..."
- Barrington-Leigh, C. P., "Elves : Ionospheric Heating By the Electromagnetic Pulses from Lightning (A primer)". Space Science Lab, Berkeley.
- "Darwin Sprites '97". Space Physics Group, University of Otago.
- Gibbs, W. Wayt, "Sprites and Elves : Lightning's strange cousins flicker faster than light itself". San Francisco. ScientificAmerican.com.
- Barrington-Leigh, Christopher, "VLF Research at Palmer Station".
- Sprites, jets and TLE pictures and articles
- High speed video (10,000 frame/s) taken by Hans Stenbaek-Nielsen, University of Alaska
- Video Reveals 'Sprite' Lightning Secrets, Livescience article, 2007.
- Gigantic Jets Over Oklahoma An Astronomy Picture of the DayAstronomy Picture of the DayAstronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...
article with pictures and video of two separate gigantic jets above OklahomaOklahomaOklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state... - Gigantic jets between a thundercloud and the ionosphere.
- Huge Mystery Flashes Seen In Outer Atmosphere
- Sprite Gallery
- http://www.nssl.noaa.gov/primer/lightning/ltg_tle.html
- http://elf.gi.alaska.edu/