Nav: Home

Thunderbolt of lightning, gamma rays exciting

June 25, 2019

University of Tokyo graduate student Yuuki Wada with colleagues from Japan discover a connection between lightning strikes and two kinds of gamma-ray phenomena in thunderclouds. The research suggests that in certain conditions, weak gamma-ray glows from thunderclouds may precede lightning bolts and their accompanying gamma-ray flashes.

In the city of Kanazawa, Ishikawa Prefecture, in central Japan, Wada and colleagues work with local schools and businesses to install radiation monitors onto buildings. These radiation monitors are not there due to some worry about local radiation levels, though. They form a network, the purpose of which is to detect radiation coming from the sky. It may surprise some, but it's been known for around 30 years that thunderstorms can bring with them gamma-ray activity.

"Forever, people have seen lightning and heard thunder. These were the ways we could experience this power of nature," said Wada. "With the discovery of electromagnetism, scientists learned to see lightning with radio receivers. But now we can observe lightning in gamma rays - ionizing radiation. It's like having four eyes to study the phenomena."

There are two known kinds of gamma-ray phenomena associated with thunderclouds: gamma-ray glows, weak emissions which last about a minute, and short-lived terrestrial gamma-ray flashes (TGFs), which occur as lightning strikes and are much more intense than gamma-ray glows. Both occur in regions of thunderclouds sandwiched between layers of varying charge. The charged regions accelerate electrons to near the speed of light. At these speeds, referred to as relativistic, electrons that stray very close to the nuclei of nitrogen atoms in the air slow down a little and emit a telltale gamma ray. This is called bremsstrahlung radiation.

"During a winter thunderstorm in Kanazawa, our monitors detected a simultaneous TGF and lightning strike. This is fairly common, but interestingly we also saw a gamma-ray glow in the same area at the same time," continued Wada. "Furthermore, the glow abruptly disappeared when the lightning struck. We can say conclusively the events are intimately connected and this is the first time this connection has been observed."

The mechanism underlying lightning discharge is highly sought after and this research may offer previously unknown insights. Wada and team intend to further their investigation to explore the possibility that gamma-ray glows don't just precede lightning strikes, but may in fact cause them. Radiation levels of the gamma-ray flashes are quite low, approximately a tenth the level one may receive from a typical medical X-ray.

"Our finding marks a milestone in lightning research and we will soon double our number of radiation sensors from 23 to about 40 or 50. With more sensors, we could greatly improve predictive models," explained Wada. "It's hard to say right now, but with sufficient sensor data, we may be able to predict lightning strikes within about 10 minutes of them happening and within around 2 kilometers of where they happen. I'm excited to be part of this ongoing research."

Further investigations will likely still take place in Kanazawa as the area has rare and ideal meteorological conditions for this kind of work. Most radiation observations in storms come from airborne or mountain-based stations as thunderclouds are generally very high up. But winter storms in Kanazawa bring thunderclouds surprisingly close to the ground, ideal for study with the low-cost portable monitors developed by the research team.

The researchers created these unique portable radiation monitors in part with technology derived from space-based satellite observatories designed for astrophysics experiments. This is appropriate as the data from this kind of research could be useful for those who research astrophysics and in particular solar physics in the context of particle acceleration. But there is a more down-to-earth offshoot as well.

"Paleontologists who study life from the last 50,000 years or so use a technique called carbon-14 dating to determine the age of a sample. The technique relies on knowledge of the levels of two kinds of carbon, carbon-12 and carbon-14," said Wada. "It's commonly thought carbon-14 is created by cosmic rays at a roughly constant rate, hence the predictive power of the technique. But there's a suggestion thunderstorms may alter the ratio of carbon-12 to carbon-14, which may slightly change the accuracy of or calibration required for carbon-14 dating to work."

Wada and colleagues will continue to unpick the mysteries of lightning, one of nature's most captivating and iconic phenomena. An upcoming collaborative project based in France will launch a dedicated satellite for worldwide lightning observations from space.
-end-


University of Tokyo

Related Gamma Rays Articles:

Medical gamma-ray camera is now palm-sized
Researchers invented a Compton camera of 580g which visualizes gamma rays of arbitrary energies, and succeeded in achieving a high-resolution, multicolor 3-D molecular image of a live mouse administered with three different radioactive tracers in just two hours.
NASA's Fermi sees gamma rays from 'hidden' solar flares
NASA's Fermi Gamma-ray Space Telescope has observed high-energy light from solar eruptions located on the far side of the sun -- light it shouldn't be able to see.
Supercomputers fire lasers to shoot gamma ray beam
Supercomputer simulations showed UT Austin scientists a new way to generate controlled beam of gamma rays from lasers.
Novel portable diagnostic tool pairs optical and gamma imaging
Bigger isn't always better, especially when it comes to a new and surprisingly portable molecular imaging system that combines optical imaging at the surface level and scintigraphy, which captures the physiological function of what lies beneath, announced developers at the 2016 Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging (SNMMI).
Gamma-retroviruses preferentially integrate near cancer-associated genes
Identifying the sites where gamma-retroviruses commonly insert into the genome may help to identify genes associated with specific cancer types, according to a study published April 20, 2016 in the open-access journal PLOS ONE by Kathryn Gilroy at the University of Glasgow, UK, and colleagues.
Galactic center's gamma rays unlikely to originate from dark matter, evidence shows
Studies by two independent groups from the US and the Netherlands have found that gamma ray signals from the inner galaxy come from a new source rather than from the collision of dark matter particles.
Gamma rays from distant galaxy tell story of an escape
A flare of very high-energy gamma rays emitted from a galaxy halfway across the universe has put new bounds on the amount of background light in the universe and given astrophysicists clues to how and where such gamma rays are produced.
VERITAS detects gamma rays from galaxy halfway across the visible universe
In April 2015, after traveling for about half the age of the universe, a flood of powerful gamma rays from a distant galaxy slammed into Earth's atmosphere.
NASA's Swift spots its thousandth gamma-ray burst
NASA's Swift spacecraft has detected its 1,000th gamma-ray burst (GRB).
Detection of gamma rays from a newly discovered dwarf galaxy may point to dark matter
A newly discovered dwarf galaxy orbiting our own Milky Way has offered up a surprise -- it appears to be radiating gamma rays, according to an analysis by physicists at Carnegie Mellon, Brown, and Cambridge universities.

Related Gamma Rays Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...