Antimatter in thundercloud doesn’t fit expectations

Nature : The production of positrons by thunderstorms is a well-established phenomenon. Electrons are accelerated by the buildup of charge in clouds and release gamma rays, which can produce an electron–positron pair when they hit an atomic nucleus. However, in 2009 Joseph Dwyer of the University of New Hampshire in Durham and his colleagues detected the presence of positrons whose characteristics did not match those of previously detected thunderstorm antimatter. While flying a plane carrying a gamma-ray detector to study cosmic-ray collisions, the researchers accidentally flew into a strong thunderstorm. The detector picked up three extremely short-lived gamma-ray signals whose energies suggested the plane had flown into an antimatter cloud 1–2 km across. After five years of attempting to model a possible explanation with no success, Dwyer’s team is publishing its data in hopes that further observations could provide a solution.