In article , rickman wrote:

Very little FM, but as the EMF generated by lightning ranges from near
DC to gamma rays, you likely need to be a bit more specific.

Gamma rays...? Really?

Yup. First discovered over 20 years ago.

http://en.wikipedia.org/wiki/Terrest...amma-ray_flash

I've seen more recent reports that suggest that the gamma-ray (and, I
think, X-ray) flux near a lighting stroke can be quite
strong... possibly enough to pose a health hazard to those nearby. It
was suggested that this could be another good reason for commercial
airplanes to avoid flying near thunderstorm cells. Although a
lightning stroke on an airplane does not generally present a shock
hazard to the passengers and crew (the metal body makes a good Faraday
cage) there might actually be enough gamma/X-radiation from the stroke
to give people onboard a hazardous dose.