More natural radiation !! ....be scared ! ..be very scared !!
**** abandon all high-rise buildings, since they attract higher-than-normal lightning strike frequency ****
**** windmill farms must be an absolute radiation hell, what with hundreds of those huge towers attracting all the lightning strikes in the area ****
**** windmill farms should certainly not be sited anywhere near farm fields, as this would cause the crops to get irradiated, and the Sierra Club says that's dangerous ****
PS. should be interesting what eventually comes out of this research -- the article doesn't mention other, older reports of neutrons having been recorded from lightning -- were those result bogus or not ? ...if not, what was the source of those neutrons ? ....low-level ICF of hail stones, as some claimed ?
FLORIDA RESEARCHERS: LIGHTNING EMITS
Modern-day Ben Franklins use rockets to settle 80-year-old debate
GAINESVILLE, Fla. --- Anyone who has heard a radio crackle
during a storm
knows lightning emits radio signals.
But in a series of unique experiments that involved firing wire-trailing
rockets into storm clouds, a team of Florida researchers has found that
"triggered" lightning also emits waves of energy much higher up the
frequency scale - X-rays, or possibly gamma rays or relativistic electrons.
Set to be reported Friday in the journal Science, the finding comes on the
heels of a similar discovery for natural lightning reported last year,
suggesting that all lightning emits such so-called energetic radiation.
Not only might the discovery finally settle a question that has been debated for
80 years, it also is among the rare instances where such high-energy,
high-frequency radiation has been reported in atmospheric conditions.
Vacuum tubes in doctor's office machines can produce X-rays on Earth, but otherwise
X-rays and gamma rays generally occur only in outer space, where they are
propagated by such extraordinary events as supernova explosions. [ hmmm -- no gammas from NORMs in the ground ?? - J.]
"I think it's really exciting," said Martin Uman, a lightning expert and
director of the University of Florida's International Center for Lightning
Research and Testing, where the experiments were done. "We didn't expect to
see anything at all, and then, all of a sudden, with almost every lightning
stroke, we had X-rays."
Debate over whether lightning emits energetic radiation dates back to the
1920s, when Nobel Prize physicist Charles Thomson Rees Wilson first
predicted the phenomenon. Numerous researchers have attempted to confirm or
refute his prediction, but results have proved inconclusive. That's because
natural lightning is devilishly hard to study, said Joe Dwyer, the lead
investigator on the project and an assistant professor of physics and space
science at the Florida Institute of Technology.
While there is no practical application for the discovery, it enhances the
basic understanding of lightning, which aids in development of lightning
protection systems, he said. X-rays, gamma rays and relativistic electrons
travel only a few hundred yards at most through the air at sea level, Dwyer said.
Because no one knows where lightning will strike, obtaining accurate
measurements can be a matter of extraordinary luck rather than repeatable
experiment. Researchers also have been hamstrung by the difficulty of
distinguishing interference from true measurements. As a result, Dwyer said,
"there have been a whole long series of results, with roughly half positive and half negative."
Dywer set out to obtain a more conclusive result. Rather than chase natural
lightning, he turned to the UF engineering college's lightning research and
testing center in rural North Florida. Researchers at the facility, located
at Camp Blanding near Starke, spark lightning by launching slender rockets
from batteries of steel tubes 2,400 feet toward passing storm clouds. Each of
the rockets trails a thin, Kevlar-coated wire designed to conduct the
lightning back to the targeted strike point on the ground.
Ground zero for the triggered lightning is the rocket launch tower.
Dwyer installed a carefully constructed detection system about 75 feet from this
tower. The system, contained in a heavy aluminum box with thick sides that
blocked out all signals except energetic radiation, consisted in part of two
photo multiplier tube detectors, standard equipment for measuring the radiation.
Two detectors were used so that one could act as a control.
Besides triggering the lightning, the UF group provided critical
measurements of its current and field strength. Manning the system from July
through September, the researchers triggered multiple lightning flashes.
Each flash typically contained several return strokes, or individual
lightning events that occur too quickly for the human eye to distinguish.
The detector recorded energetic radiation in 87 percent of 37 such strokes,
showing it occurred at the beginning or just before each stroke - the moment
when the charge moved down from the cloud and contacted the ground just
before the stroke.
"It's right before the visible stroke occurs - that appears to be when the
energetic radiation is being produced," Dwyer said. "Nobody really
understands completely how this is happening."
This phase of the lightning process is known as the "dart leader" and also
is present in natural lightning extending from clouds to the ground, which
suggests the findings likely apply to all cloud-to-ground lightning, Uman
said. It's also important the observations occurred near sea level, because
the lower the altitude, the harder it is for energetic radiation to generate
and propagate, he said.
Earth-orbiting satellites have recorded energetic radiation apparently
associated with thunderstorms. But few expected to see it produced at near
ground level, Dwyer said. "People didn't think the electric fields were
strong enough or that the length scales were long enough," he said.
Dwyer's project is part of a five-year, $410,000 Young Investigator Award
from the National Science Foundation, research performed in connection with
related NSF-sponsored research at UF. He plans to return to the lightning
research and testing center next summer to continue the investigation. At
the top of his priority list: narrowing down whether the energetic radiation
produced by lightning consists specifically of X-rays, gamma rays, energetic
electrons or some combination of the three. UF researchers are preparing an
improved set of supporting instruments for the experiment.
"We can go out there every summer," Dwyer said. "So it's finally become an
experimental science where we can do experiments and test theories, and it
never really was that before."
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