Rød fe

Røde feer er storskala elektriske udladninger, som sker højt over tordenvejrsskyer eller Cumulonimbusskyer. Røde feer udløses nogle gange af positive lynudladninger mellem en underliggende tordensky og jordoverfladen.^[1] Fænomenet er opkaldt efter den onde fe Ariel i Shakespeares En skærsommernatsdrøm. Røde feer har sædvanligvis en rødorange eller blågrøn farve, med hængende "tentakler" under - og en "trækrone" over. Lysfænomenet viser sig som et kort glimt. Før de opstår, kan man nogle gange se en kortvarig, rødlig halo.^[2]

Første farvebillede af en rød fe taget fra et luftfartøj (1994). Som det ses af højdeskalaen, er den røde fe omkring 40 km høj.

Røde feer dannes ofte i klynger indenfor højdeintervallet 50-90 km over jordoverfladen.^[3] Sporadiske øjenvidneberetninger om røde feer går tilbage til 1886, men røde feer blev først fotograferet den 6. juli 1989 af forskere fra University of Minnesota og er efterfølgende blevet optaget på videooptagelser mange tusinde gange.^[4]^[5]

Røde feer bliver nogle gange forkert benævnt lyn i den øvre atmosfære. Grunden til, at røde feer ikke kan kaldes lyn, skyldes, at røde feer er et koldt plasma fænomen, som derfor mangler den varme lynkanaltemperatur som troposfæriske lyn har, så røde feer er mere som neonrør-udladninger end lynudladninger.

Kilder/referencer redigér

^ Boccippio, D. J.; et al. (august 1995). "Sprites, ELF Transients, and Positive Ground Strokes". Science. 269: 1088-1091. doi:10.1126/science.269.5227.1088. PMID 17755531. {{cite journal}}: Eksplicit brug af et al. i: |first= (hjælp)
^ Sterling D. Allen - Pure Energy Systems News (2005). "BLAM-O!! Power from Lightning". Pure Energy Systems. Arkiveret fra originalen 19. oktober 2007. Hentet 5. november 2009.
^ Penn State. (2014, May 7). Sprites form at plasma irregularities in the lower ionosphere. ScienceDaily Citat: "...Sprites are an optical phenomenon that occur above thunderstorms in the D region of the ionosphere, the area of the atmosphere just above the dense lower atmosphere, about 37 to 56 miles above Earth...Sprites occur above thunderstorms, but thunderstorms, while necessary for the appearance of a sprite, are not sufficient to initiate sprites. All thunderstorms and lightning strikes do not produce sprites. Recent modeling studies show that plasma irregularities in the ionosphere are a necessary condition for the initiation of sprite streamers, but no solid proof of those irregularities existed..."
^ Walter A. Lyons and Michey D. Schmidt (2003). P1.39 The Discovery of Red Sprites as an Opportunity For Informal Science Education. American Meteorological Society.
^ July 7, 2020, Video Captures What Looks Like an Alien Invasion Over France – NASA Has a Terrestrial Explanation Citat: "...A sensitive video camera on a summit of the Vosges mountains in France captured these surprising fireworks above a distant horizon on June 26, 2020. Generated over intense thunderstorms, this one about 260 kilometers away, the brief and mysterious flashes have come to be known as red sprites..."

Se også redigér

Eksterne henvisninger redigér

"Red Sprites & Blue Jets" A digital capture of the VHS video distributed in 1994 by the University of Alaska Fairbanks that popularized the terms.
"Red Sprites and Blue Jets" Arkiveret 14. september 2002 hos hos Library of Congress webpage by University of Alaska Fairbanks
Ground and Balloon-Borne Observations of Sprites and Jets
Darwin Sprites '97 Space Physics Group, University of Otago.
Sprites, jets and TLE pictures and articles
Første danske rum-lyn blev fanget fra Silkeborg Arkiveret 6. september 2015 hos Wayback Machine, DMI, Jesper Grønne beskriver sin fotografering af red sprites

[boccippio-1] Boccippio, D. J.; et al. (august 1995). "Sprites, ELF Transients, and Positive Ground Strokes". Science. 269: 1088-1091. doi:10.1126/science.269.5227.1088. PMID 17755531. {{cite journal}}: Eksplicit brug af et al. i: |first= (hjælp)

[pesn-2] Sterling D. Allen - Pure Energy Systems News (2005). "BLAM-O!! Power from Lightning". Pure Energy Systems. Arkiveret fra originalen 19. oktober 2007. Hentet 5. november 2009.

[penn-3] Penn State. (2014, May 7). Sprites form at plasma irregularities in the lower ionosphere. ScienceDaily Citat: "...Sprites are an optical phenomenon that occur above thunderstorms in the D region of the ionosphere, the area of the atmosphere just above the dense lower atmosphere, about 37 to 56 miles above Earth...Sprites occur above thunderstorms, but thunderstorms, while necessary for the appearance of a sprite, are not sufficient to initiate sprites. All thunderstorms and lightning strikes do not produce sprites. Recent modeling studies show that plasma irregularities in the ionosphere are a necessary condition for the initiation of sprite streamers, but no solid proof of those irregularities existed..."

[4] Walter A. Lyons and Michey D. Schmidt (2003). P1.39 The Discovery of Red Sprites as an Opportunity For Informal Science Education. American Meteorological Society.

[5] July 7, 2020, Video Captures What Looks Like an Alien Invasion Over France – NASA Has a Terrestrial Explanation Citat: "...A sensitive video camera on a summit of the Vosges mountains in France captured these surprising fireworks above a distant horizon on June 26, 2020. Generated over intense thunderstorms, this one about 260 kilometers away, the brief and mysterious flashes have come to be known as red sprites..."

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