Antimatter in Lightning

From /.

"The Fermi Gamma-ray Space Telescope, launched last year,
detects gamma rays from light years away, but recently it detected gamma rays from lightning on Earth. And the energy of the gamma rays is specific to the decay of positrons, which are the antimatter flavor of electrons. Finding antimatter in lightning surprised researchers and suggests the electric field of the lightning somehow got reversed."

Again, if anti-matter + matter = Big-badda-boom, then where's the big boom?

Still looking for the paper that discusses the amount of energy released in a matter/anti-matter explosion.

Update: OK, from what I can see, there's actually 2 opinions in the scientific community relating to "anti-matter explosions". Some say that a matter/anti-matter reaction will make a large badda-boom. Others say that the anti-matter interactions with regular matter will can generate large amounts of energy, but it will be in the form of light and gamma radiation. Now by definition, energy creates heat by exciting the molecules of things it impacts upon, so I can't see how they don't define this as "explosive", but perhaps it's because there's no blast wave. As I don't have enough of a mathematical background to make heads-or-tails of the relative merits of each theory, I'll have to take their words for it.

Basically, mixing matter/anti-matter is bad, um-kay?

Here's where I did my research: Google Scholar