@a2j 19 October 2021 more from that month

Why does lightning give the night sky a purple hue? I've noticed that in any photo taken during lightning, the background sky looks purplish. It was apparent when we had lightning and thunder a few nights ago. Even though there were no bolts of lightning seen, everytime the sky glowed with distant lightning, it looked purple. When I posted a picture a few weeks ago of another thunderstorm, someone mentioned this too. What causes this pretty hue of purple during lightning? This pic is from a screengrab from the thunderstorm a few nights ago. The purple is not very apparent in this. It's a low quality image - apologies in advance.