Detection of High-Energy Gamma Rays from Winter Thunderclouds

I mentioned about an article on "Thundercloud Accelerator" a while back, where a group of Japanese physicists discovered that some of these thunderclouds can achieve such high gradients as to accelerate electrons and produce gamma rays.

The paper on this has now been published. Here is the exact reference:

H. Tsuchiya et al, Phys. Rev. Lett. v.99, p.165002 (2007).

Zz.