enfrdeelitjaptes

Phenomenon

  • Giant Jet appears in the night sky over Paraiba, Brazil

    Something out-of-this-world has been recorded in the night sky over Paraiba, Brazil on April 17, 2020.

    This gigantic jet, also known as giant jet

    The newly observed transient luminous event was luckily captured by a camera in João Pessoa, which monitors the skies 24 hours a day:

    The giant jet formed over a storm cloud close to Caicó, in Rio Grande do Norte, about 250 km from where it was recorded.

    Transient luminous event

    Gigantic jets are the rarest of the known Transient Light Events (TLEs), which are upper atmospheric optical phenomena associated with thunderstorms, like red sprites, blue jets and elves. 

    Gigantic jets were first documented in July 2002.

    They are similar to carrot-shaped red sprites in spatial extent but propagate upward from the core of oceanic thunderstorms and are not directly associated with cloud-to-ground lightning.

    They can reach an altitude of up to 90 km (56 miles).

    The giant jets are so rare that the first one in Brazil was recorded in 2017 in Taperoá, Brazil.

    Other types of Transient Luminous Events

    Red Sprites

    Red sprites are large but weak luminous flashes that appear directly above an active thunderstorm system and are coincident with powerful positive cloud-to-ground lightning strokes.

    Their spatial structures range from small single or multiple vertically elongated spots, to bright groupings which extend from above the cloud tops to altitudes up to almost 60 miles (about 95 km).

    Sprites are predominantly red and they usually last no more than a few milliseconds.

    The brightest region lies in the altitude range 40 to 45 miles (about 65-75 km), above which there is often a faint red glow or wispy structure that extends to about 55 miles (90 km).

    Below the bright red region, blue tendril-like filamentary structures often extend downward to as low as 20 miles (30 km).

    Some events are loosely packed and may extend across horizontal distances of 30 miles (50 km) or more.

    Their shapes can be variously described as resembling jellyfish, carrots, or columns. Because of their low surface brightness, they have only been imaged at night (primarily with highly sensitive cameras).

    However, if ones eyes are sufficiently dark-adapted, one can actually detect them without any visual aid.

    The first images of a sprite were accidently obtained in 1989, although anecdotal reports of “rocket-like” and other optical emissions above thunderstorms go back more than a century (see for example an early account by Johann Georg Estor.

    Early research reports for these events referred to them by a variety of names, including “upward lightning,” “upward discharges,” “cloud-to-stratosphere discharges,” and “cloud-to-ionosphere discharges.”

    Now they are simply referred to as sprites, a whimsical term that evokes a sense of their fleeting nature, while at the same time remaining nonjudgemental about physical processes that have yet to be determined.

    Blue Jets

    Blue jets are a second high altitude optical phenomenon, distinct from sprites and first documented in 1994 (although pilots had earlier reported similar sightings).

    Blue jets are optical ejections from the top of the electrically active core regions of thunderstorms, but not directly associated with cloud-to-ground lightning.

    Following their emergence from the top of the thundercloud, they typically propagate upward in narrow cones of about 15 degrees, fanning out and disappearing at heights of about 25-30 miles (40-50 km) with a lifetime of a couple of tenths of a second.

    Blue Starters

    Blue starters differ from blue jets in that the are brighter but shorter (reaching to only about 12 miles altitude).

    These were reported to occur over regions where large hailstones were falling.

    Upward Lightning

    Upward lightning is similar to a conventional lightning bolt, generally rather straight and may be tilted off vertical axis, but does not flicker like cloud-to-ground flashes.

    Lasts one, two and even 5 seconds with a yellow or white lightning channel, maybe with blue flames above.

    Elves

    Elves are rapidly expanding (up to 300 miles across) disk-shaped regions of luminosity, lasting less than a thousandth of a second, which occur high above energetic cloud-to-ground lightning of positive or negative polarity.

    Elves most likely result when an energetic electromagnetic pulse (EMP) propagates into the ionosphere. Though they can be accompanied by sprites, the causative mechanism is of an entirely different nature.

    Predicted to exist in 1991and discovered with a low-light video camera aboard the Space Shuttle in 1992, elves got their name as an acronym for Emission of Light and Very Low Frequency perturbations due to Electromagnetic Pulse Sources.

    Sprite Halos

    Sprite halos were mistaken as elves until 1999. They are diffuse disk shaped glows that apparently precede sprites and propagate downward from about 50 miles to 40 miles (85 to 70 km) altitude and last about a millisecond.

    Trolls

    Trolls, also recently observed, resemble blue jets, but are red and seem to occur after tendrils of vigorous sprites extend downward toward the cloud tops.

    Gnomes

    Gnomes are possibly just a different manifestation of blue starters but appear with a more compact shape above convective domes.

    Pixies

    Pixies are pinpoints of light, lasting less than 16 milliseconds, on the surface of convective domes that produced gnomes.

    Gigantic Jets

    Gigantic jets, first documented in July 2002, are similar to carrot-shaped red sprites in spatial extent but propagate upward from the core of oceanic thunderstorms and are not directly associated with cloud-to-ground lightning.

  • Red sprites and airglow sky phenomenon over West Texas

    A large column of red sprites and airglow put on a fantastic display over West Texas on May 13, 2020. The phenomenon was captured by Stephen Hummel of the McDonald Observatory.

    A line of storms more than 161 km (100 miles) away generated the astonishing display in the upper atmosphere over Alpine city.

    "I saw a large column of sprites leaping into the sky and rushed to set up my camera," said Hummel. He was walking across the University of Texas observatory grounds hours after the sunset when a flash of lightning from a distant thunderstorm caught his eye.

    The 45-minute timelapse shows alternating bands of red and green airglow, gliding in a motion similar to ripples in water. Red bolts of upward-directed lightning or sprites flashed brightly at the same time.

    "I could see them with my unaided eye," Hummel added. "It was a fantastic display."

    "I had just hiked to the top of a ridge for a better view, and was a little out of breath as I set up my camera," he further explained.

    "Just then I heard the eerie sound of a mountain lion's call. I left the camera running while I returned to the safety indoors! Later, I gathered the footage, hoping for the best. I was amazed by the results and surprised the airglow was so evident."

    The thunderstorm was convective with powerful updrafts. It slammed the upper atmosphere from below, generating a spot-on pattern of pressure waves in the mesosphere more than 80 km (50 miles) above the ground. 

    The pattern impressed itself upon the airglow layer close to the edge of space, creating aurora-like colors that are often too faint to be observed.

    According to SpaceWeather.com, more sprites and atmospheric bullseyes are in the offing, especially now that northern spring is thunderstorm season-- the best time to catch such events

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