There is a huge potential difference between the Earth and the upper atmosphere that is responsible for world-wide lightning discharges at a rate of about fifty or sixty strikes per second. The Japanese have been using lasers to encourage these strikes for the purpose of testing the survivabilty of high-voltage power transmission lines. Many years ago I had a similar idea of using an orbiting high-power infrared and coaxial ultraviolet laser to establish an ionized conducting path to "bring down the lightning" as a weapon, but the idea went nowhere AFAIK. Probably has something to do with not wanting to put weapons in space and starting a race for world domination. Where's Lex Luthor when you want to field really radical ideas?