Gamma Rays From Thunderclouds

KentuckyFC sends us a report of gamma rays detected at a Japanese nuclear plant, whose origin was thunderclouds high overhead (abstract, article PDF). The theory is that showers of electrons caused by cosmic rays, when they encounter the high electric fields present in thunderstorm clouds, can be accelerated to energies above 10 MeV and result in bremsstrahlung photons detectable on the ground.

Re:Or Lightning Fusing Hydrogen?

[Anonymous Coward]

Actually, fusion should produce fast neutrons, not gamma rays.

Re:Wow. That's some high energy Gamma Rays

[niklask]

Correct me if I'm wrong, but don't we have NO way to detect electrons that don't strike normal matter? As in, if I send a stream of electrons 10 meters away from you in your spaceship, aren't you completely oblivious to what I did if I missed?

You are wrong. Electrons in magnetic fields radiate synchrotron radiation and wee know that the Solar system and the Milky Way is pervaded by magnetic fields.

Re:Radiation Overdose?

[Wilson_6500]

Ionizing radiation is much like most other poisons in that dose is critical in determining subsequent health effects. You are--right now--not only being bombarded by tiny amounts of ionizing radiation from most things around you, but your body tissues themselves are releasing ionizing radiation: they contain completely natural but radioactive potassium-40. It is, however, a very, very low level of radiation.

According to our best theories--which, to be honest, are not by any means set in stone--there is no absolutely safe lower threshold for radiation exposure IF you consider the chances for causing cancer and genetic effects. These are called "stochastic" radiation effects, because they are best described in terms of risk and probability and do not have definite thresholds. For acute radiation toxicity--vomiting, blistering, and so on--there are fairly well-defined threshold doses; these radiation sicknesses are called "deterministic" effects because we can safely say that, given a certain amount of damage, you have a certain (high) chance of acute radiation sickness. These latter effects are similar to other toxic substances, in that they are talked about in terms of doses that have some specific chance (say, 50% or 99%) of causing an effect.

The amount of radiation-induced damage caused by the gammas released by a thunderstorm is very likely to be well below the thresholds for deterministic effecs, which means that an average person has essentially no chance of developing acute radiation sickness from a thunderstorm. Exposure to low levels of radiation may increase your chance of developing cancer, but such an increase is naturally impossible to quantify.