Now it's looking as if antimatter might not be quite so exotic as we thought; thunderstorms might routinely produce antimatter beams via a byproduct of lightning known as a terrestrial gamma ray flash (TGF).
Until quite recently, scientists believed that most gamma-rays are produced by cataclysmic events in distant galaxies, such as the death of supermassive stars. But thanks to the advent of gamma-ray telescopes, like Fermi, we've known about terrestrial gamma radiation since 1994 –"probably the last place we ever expected to see ," Gerald Fishman, an astrophysicist at NASA's Marshall Space Flight Center, told Discovery News last year.
One way to create such short bursts of gamma rays is through the collision - and subsequent annihilation, as the mass of those particles converts into energy - of an electron and a positron. The Fermi Space Telescope found hints in 2009 of the telltale pattern associated with positrons in terrestrial gamma rays stemming from lightning storms.
Under the right conditions, strong electric fields - the kind typically found near the tops of thunderstorms - can trigger an upward avalanche of high-energy electronics that in turn interact with the atmosphere to create a natural "particle accelerator," particularly when combined with the cosmic rays that routinely bombard Earth's atmosphere. (Such avalanches may also be what triggers lightning.) All those high-energy electrons emit gamma rays whenever they're deflected by air molecules in the atmosphere, and these are usually detected as a TGF.