Does anyone really think that we have lightening figured out?
Besides gamma rays and errant electrons we also have stripped atoms
accumulating and moving around to form ball lightening also. In fact
a channel may well be formed by stripped ions. The ball lightening
was only recently properly described.
A good explanation may be that we are actually seeing a heat effect
penetrating the air mass as the surplus electrons drill toward the
ground. Once the ions are hot enough the electrons are able to
cascade easily through the mass of ions.
Once the potential becomes large enough it is released by heating up
atoms through both shock waves in heat lightening and bolt generation
which grounds the potential. With heat lightening, imagine the potential becoming large enough and dense enough to allow explosive separation caused by shifting electrons leaving stripped atoms.
It is still all pretty dramatic.
Scientists Detect
Dark Lightning Linked To Visible Lightning
by Staff Writers
Washington DC (SPX) Apr 25, 2013
Three images, left to
right, of the same thundercloud depict a
less-than-10-milliseconds-long sequence of events: (left) formation
within the cloud of a small channel, or 'leader,' of electrical
conductivity (yellow line) with weak emission of radio signals
(ripples), to (middle) a burst of both dark lightning (pink) and
radio waves (larger ripples), to (right) a discharge of bright
lightning and more radio waves. (Credit: Studio Gohde). For a larger
version of this image please go here.
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
Ostgaard, 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 (190 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,
Ostgaard 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
Ostgaard. 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," Ostgaard 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 (1,900 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 Ostgaard and his team used to reconstruct this ethereal
electrical event, which lasted 300 milliseconds.
Ostgaard 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,
Ostgaard 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
Ostgaard, 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, Ostgaard 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."
"Simultaneous
observations of optical lightning and terrestrial gamma-ray flash
from space" Authors: N. Ostgaard 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 Huntsville, Alabama, USA.
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