In "Lightning above the clouds, "Alejandro Luque, Ute Ebert and browse more than twenty years of research on TLEs (Transient Luminous Events ), taking stock of the situation and pointing out unresolved issues.
Luque Ebert and draw a short story from 1989 when science takes note of this elusive phenomenon, from the first capture of a random pair of Sprite, which occurred during testing as we know a camera's high-brightness, pointed to a lightning storm.
John R. Winckler (University of Minnesota), he realized he had found something unknown, and this rare phenomenon became part of the class of phenomena of the mesosphere, ionosphere, and soon ended up losing its uniqueness, both quantitatively and qualitatively, came to occupy an increasingly important role in research, physical and chemical phenomena of the atmosphere.
Sprite had been theorized as a phenomenal opportunity in 1925 by Wilson, but scientists had never taken the time to investigate this hypothetical reality, however, already appeared in occasional sporadic evidence, reported in scientific journals.
Luque and Ebert reminds us that to understand Sprite and it must be assumed by the TLE understanding of lightning.
We know that the lightning discharge is developed in three phases. In the first stage, the collision of ice particles and water droplets together with the gravity separating positive and negative charges in the thundercloud. So the download grows, forming a branching streamer-leader named .
E 'on this second phase are now betting that the attention of the research on lightning.
The fact is that in the lightning, including lightning, the electric field is almost always at the back of an order or three below the value of the magnitude required for the breakdown . Therefore, a
simple avalanche ionization, linear, can not develop.
The basic mechanism in these circumstances is provided by so-called "streamers" , a sort of adventurers that open via a non-ionized air, and to consolidate the successive waves of ionization.
The authors explain how these streamers are an important process because of the elusive lightning discharge. The second streamer
that appears is above the temporal form of Sprite, similar to that which opens the way to lightening.
This was confirmed by high-speed shooting, and the photo lab with exposure times of nanoseconds.
The study of sprites, through these recordings and the use of spectroscopy can reveal many secrets of the mesosphere.
Of great help were the search space, which began in 2004, where even the European Research Area (ESA and CNES) have played an important role.
Luque and Ebert also emphasized the importance of computer modeling, which was part of their work since 2009.
An example is the beginning of a Sprite from the HAL (discoid light emission that begins in the lower atmosphere and often precedes the Sprite).
Through their model the authors have suggested that the top of the streamer that generates the Sprite has a negative charge.
Luque e Ebert concludono che ancora molte domande interessanti attendono una risposta: 1) cosa ci dicono gli Sprite sullo stato della mesosfera e della ionosfera? 2) quanti gas-serra sono prodotti da fulmini e Sprite, e a che livello della scarica ciò accade? 3) c'è una relazione tra TGFs ( Terrestrial Gamma-Ray Flashes ) e Sprite? 4) Esistono fenomeni tipo Sprite su altri pianeti?
Evidentemente il tentativo di soluzione di tutti questi quesiti può generare una serie di importanti ricadute tecnologiche.
Luque Alejandro & Ebert Ute, "Lightning above the clouds" , vol. 41, n. 5, riv. Europhysics News, 2010, pp. 19-22
[info Renzo Cabassi; source: http://www.europhysicsnews.org/]
Luque Ebert and draw a short story from 1989 when science takes note of this elusive phenomenon, from the first capture of a random pair of Sprite, which occurred during testing as we know a camera's high-brightness, pointed to a lightning storm.
John R. Winckler (University of Minnesota), he realized he had found something unknown, and this rare phenomenon became part of the class of phenomena of the mesosphere, ionosphere, and soon ended up losing its uniqueness, both quantitatively and qualitatively, came to occupy an increasingly important role in research, physical and chemical phenomena of the atmosphere.
Sprite had been theorized as a phenomenal opportunity in 1925 by Wilson, but scientists had never taken the time to investigate this hypothetical reality, however, already appeared in occasional sporadic evidence, reported in scientific journals.
Luque and Ebert reminds us that to understand Sprite and it must be assumed by the TLE understanding of lightning.
We know that the lightning discharge is developed in three phases. In the first stage, the collision of ice particles and water droplets together with the gravity separating positive and negative charges in the thundercloud. So the download grows, forming a branching streamer-leader named .
E 'on this second phase are now betting that the attention of the research on lightning.
The fact is that in the lightning, including lightning, the electric field is almost always at the back of an order or three below the value of the magnitude required for the breakdown . Therefore, a
simple avalanche ionization, linear, can not develop.
The basic mechanism in these circumstances is provided by so-called "streamers" , a sort of adventurers that open via a non-ionized air, and to consolidate the successive waves of ionization.
The authors explain how these streamers are an important process because of the elusive lightning discharge. The second streamer
that appears is above the temporal form of Sprite, similar to that which opens the way to lightening.
This was confirmed by high-speed shooting, and the photo lab with exposure times of nanoseconds.
The study of sprites, through these recordings and the use of spectroscopy can reveal many secrets of the mesosphere.
Of great help were the search space, which began in 2004, where even the European Research Area (ESA and CNES) have played an important role.
Luque and Ebert also emphasized the importance of computer modeling, which was part of their work since 2009.
An example is the beginning of a Sprite from the HAL (discoid light emission that begins in the lower atmosphere and often precedes the Sprite).
Through their model the authors have suggested that the top of the streamer that generates the Sprite has a negative charge.
Luque e Ebert concludono che ancora molte domande interessanti attendono una risposta: 1) cosa ci dicono gli Sprite sullo stato della mesosfera e della ionosfera? 2) quanti gas-serra sono prodotti da fulmini e Sprite, e a che livello della scarica ciò accade? 3) c'è una relazione tra TGFs ( Terrestrial Gamma-Ray Flashes ) e Sprite? 4) Esistono fenomeni tipo Sprite su altri pianeti?
Evidentemente il tentativo di soluzione di tutti questi quesiti può generare una serie di importanti ricadute tecnologiche.
Luque Alejandro & Ebert Ute, "Lightning above the clouds" , vol. 41, n. 5, riv. Europhysics News, 2010, pp. 19-22
[info Renzo Cabassi; source: http://www.europhysicsnews.org/]
