Isn't thunder created by the vacuum of a collapsing ion trail from the lightning itself?
So the lightning creates a super charged plasma, and that heat and ionization forms a vacuum. Coupled with anti-matter and xray burst you get your perfect Gamma-Ray engine.
Now I did read that we could scan for life outside our solar system by looking for ionized light -- seems that the "left-handed chirality" of amino acids is do to the right-handedness of the more common organic compounds that a Yellow star creates. The right and left-handed carbon compounds cancel out over many reactions and the slight nod to right-handed means they are more plentiful. Since "more building blocks" equals less energy, life -- at least on earth, ended up being left-handed chemical bonds.
A plethora of left-handed carbon compounds on a planet full of life means that the light that bounces off of it will be polarized.
However -- if we can say that Lightning is created on planets with magnetospheres and oxygen, and likely is the catalyst for life (well, that's my guess -- regards to Mary Shelley). Then we might "more easily" find likely life-baring planets by detecting Gamma-Ray bursts. Should stick out more than polarized light.
Detecting both gamma-ray and polarization might give us a statistical probability for life. We will need some actual sample data more than one, however.