Thunderstorms spew out gamma rays — these scientists want to know why

Researchers in Japan are enlisting an army of citizens to explore how storms on Earth create extreme bursts of radiation.

more…

Tau.Neutrino said:

Thunderstorms spew out gamma rays — these scientists want to know why

Researchers in Japan are enlisting an army of citizens to explore how storms on Earth create extreme bursts of radiation.

more…

> In their first campaign, the researchers installed 16 detectors in Kanazawa and surrounding cities and, in 2017, made a major discovery. They observed a series of telltale γ-ray signals, which could only be caused by nuclear reactions in thunderstorms. Their landmark findings proved that γ-rays could knock neutrons out of atoms in the air, making them radioactive. That finding confirmed the existence of a hypothesized process that produces some of the atmosphere’s supply of radioactive carbon-14.

> Enoto has worked with a private company to design an even smaller, cheaper γ-ray detector, which his team plans to distribute to citizen scientists around the city to install and operate. Compact Gamma-ray Monitor or CoGaMo.

Sounds like fun.

> Enoto’s team wants to use its detectors to understand the size of γ-ray emitting regions, and how they vary in time and space and with a cloud’s movement.

Good.

> the strong electric field in thunderclouds. The field forms when rising streams of air carry ice crystals upwards past falling hail — friction between the two creates separate pools of negatively and positively charged particles in different parts of the cloud. Those fields are natural particle accelerators. If a very high-energy electron (perhaps generated by a cosmic ray from outer space) enters the cloud’s electric field, it can overcome the friction of air to accelerate to close to the speed of light. When that electron hits an air atom, it releases the kind of γ-ray seen in glows and flashes, in a process known as bremsstrahlung radiation. Electrons multiply because each collision can knock further electrons out of the atoms in a chain reaction, creating an avalanche of particles and a flood of γ-rays.

> Researchers have posed two main possibilities. One hypothesis suggests that the electrons are released at the tip of lightning ‘leaders’ — the narrow conductive channels that occur before the larger visible lightning current. According to this idea, the extreme electric field at the tip of a leader can ionize the air, creating trillions of ‘seed’ electrons. Another proposed mechanism, which Dwyer has termed dark lightning, says that the avalanche process itself would result in many more electrons than initially proposed, because some of the γ-rays created by high-energy electrons would trigger whole new cascades — an avalanche of avalanches.

> The team now sees as many as 20 glows a year in Kanazawa.

> The team wants to use its array to track glows as they drift for kilometres, to learn about the lifetime of the strong electric fields in storms that create them, including how particle acceleration starts, how it develops and what stops it. In 2019, the team became the first to definitively show a growing glow suddenly terminating with a γ-ray flash, as well as lightning.

What’s wrong with this idea? Radiation from all sources (including gamma rays from lightning) would show up passing through an orange in the dark as Cherenkov radiation, which is blue. So keep a photocell tuned to the blue spectrum on an orange in the dark to detect gamma rays from lightning.

————-

While talking lightning, how easily could a corona glow or St Elmo’s fire set something (like a butterfly or bat) on fire?