Can anyone confirm...
 

...that there is lightning when playing/designing a single player mission. I am trying to mod lightning, see here...

http://www.subsim.com/radioroom/showthread.php?t=99668

and I am testing in a single mission. I have heard thunder but not actually seen a bolt of lightning.

Has anyone?

If it does occur then I can assume that a value I have changed is the cause.

Have seen it while playing a career...not sure if you can arrange with mission editor though...

I have seen lightning bolts in a career game several times. Not sure the whereabouts of the files that control it. I'd assume there is a .TGA file somewhere that covers it.