From Ed Prior, Poquoson, Virginia, US
When I worked at NASA Langley Research Center in Hampton, Virginia, a number of astronauts on the International Space Station reported a huge number of lightning flashes happening simultaneously all over the planet. Some of them thought the flashes were somehow communicating with each other.
Shannon Hall discusses the billions of high-energy cosmic rays that crash into our atmosphere and their effect on thunderstorms (15 April, p 37). These could well be the worldwide trigger for lightning strikes.
