The Fermi Gamma-Ray Space Telescope has detected several lightning strikes that created positrons. It was built to detect gamma rays, mostly from our sun, but also detects them from lightning in the atmosphere. Over 14 months, 17 times it has found gamma rays that could only be created by the decay of antimatter.
During two recent lightning storms, Fermi recorded gamma-ray emissions of a particular energy that could have been produced only by the decay of energetic positrons, the antimatter equivalent of electrons. The observations are the first of their kind for lightning storms. Michael Briggs of the University of Alabama in Huntsville announced the puzzling findings November 5 at the 2009 Fermi Symposium.