Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists detect dark lightning linked to visible lightning

25.04.2013
Researchers have identified a burst of high-energy radiation known as ‘dark lightning” immediately preceding a flash of ordinary lightning. The new finding provides observational evidence that the two phenomena are connected, although the exact nature of the relationship between ordinary bright lightning and the dark variety is still unclear, the scientists said.

“Our results indicate that both these phenomena, dark and bright lightning, are intrinsic processes in the discharge of lightning,” said Nikolai Østgaard, who is a space scientist at the University of Bergen in Norway and led the research team.

He and his collaborators describe their findings in an article recently accepted in Geophysical Research Letters—a journal of the American Geophysical Union.

Dark lightning is a burst of gamma rays produced during thunderstorms by extremely fast moving electrons colliding with air molecules. Researchers refer to such a burst as a terrestrial gamma ray flash.

Dark lightning is the most energetic radiation produced naturally on Earth, but was unknown before 1991. While scientists now know that dark lightning naturally occurs in thunderstorms, they do not know how frequently these flashes take place or whether visible lightning always accompanies them.

In 2006, two independent satellites—one equipped with an optical detector and the other carrying a gamma ray detector—coincidentally flew within 300 kilometers (186 miles) of a Venezuelan storm as a powerful lightning bolt exploded within a thundercloud. Scientists were unaware then that a weak flash of dark lightning had preceded the bright lightning.

But last year, Østgaard and his colleagues discovered the previously unknown gamma ray burst while reprocessing the satellite data. “We developed a new, improved search algorithm…and identified more than twice as many terrestrial gamma flashes than originally reported,” said Østgaard. He and his team detected the gamma ray flash and a discharge of radio waves immediately preceding the visible lightning.

“This observation was really lucky,” Østgaard said. “It was fortuitous that two independent satellites—which are traveling at 7 kilometers per second (4.3 miles per second)—passed right above the same thunderstorm right as the pulse occurred.” A radio receiver located 3,000 kilometers (1864 miles) away at Duke University in Durham, North Carolina detected the radio discharge.

The satellites’ observations combined with radio-wave data provided the information that Østgaard and his team used to reconstruct this ethereal electrical event, which lasted 300 milliseconds.

Østgaard and his team suspect that the flash of dark lightning was triggered by the strong electric field that developed immediately before the visible lightning. This strong field created a cascade of electrons moving at close to the speed of light. When those relativistic electrons collided with air molecules, they generated gamma rays and lower energy electrons that were the main electric current carrier that produced the strong radio pulse before the visible lightning.

Dark and bright lightning may be intrinsic processes in the discharge of lightning, Østgaard said, but he stressed that more research needs to be done to elucidate the link.

The European Space Agency is planning on launching the Atmospheric Space Interactions Monitor (ASIM) within the next three years, which will be able to better detect both dark and visible lightning from space, said Østgaard, who is part of the team that is building the ASIM gamma-ray detector.

Dark lightning has remained a perplexing phenomenon due to scientific limitations and a dearth of measurements, Østgaard explained.

“Dark lightning might be a natural process of lightning that we were completely unaware of before 1991,” he noted. “But it is right above our heads, which makes it very fascinating.”

A grant from the European Research Council and the Research Council of Norway funded this research.

Notes for Journalists

Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this accepted article by clicking on this link: http://onlinelibrary.wiley.com/doi/10.1002/grl.50466/abstract

Or, you may order a copy of the final paper by emailing your request to Sarah Charley at scharley@agu.org. Please provide your name, the name of your publication, and your phone number.

Neither the paper nor this press release are under embargo.

Title:

“Simultaneous observations of optical lightning and terrestrial gamma ray flash from space”
Authors:
N. Østgaard and T. Gjesteland Birkeland Centre for Space Science, University of Bergen, Norway and Department of Physics and Technology, University of Bergen, Norway;B. E. Carlson Birkeland Centre for Space Science, University of Bergen, Norway, Department of Physics, Technology, University of Bergen, Norway, and Carthage College, Kenosha, Wisconsin, USA;A. B. Collier South African National Space Agency Space Science, South Africa, and University of KwaZulu-Natal, South Africa;S. A. Cummer and G. Lu Electrical and Computer Engineering Department, Duke University, North Carolina, USA;H. J. Christian University of Alabama in Hunstville, Alabama, USA.

Contact information for the author:

Nikolai Østgaard, Cell: +47 4727 0653, Phone: +47 5558 2794, Email: nikolai.ostgaard@ift.uib.no

AGU Contacts:
Sarah Charley
+1 (202) 777-7516
scharley@agu.org
Peter Weiss
+1 (202) 777-7507
pweiss@agu.org
University of Bergen Birkeland Centre for Space Science Media Relations Contact
Arve Aksnes
Phone: +47 55 58 81 53
Cellphone: +47 480 26 563
Arve.Aksnes@mnfa.uib.no

Peter Weiss | American Geophysical Union
Further information:
http://www.agu.org

More articles from Earth Sciences:

nachricht NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center

nachricht Steep rise of the Bernese Alps
24.03.2017 | Universität Bern

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>