New evidence suggests that large storms, similar to thunderstorms on Earth, but made of dry ice (carbon dioxide crystals) may form frequently over Mars' poles.

http://news.nationalgeographic.com/news/20...9_mars_ice.html

I wouldn't want to be caught in one...!

I wonder if they could detect lighting with night side imaging?

No need - listen out via radio! Now that'd be a good experiment for a NetLander or whatever...

Bob Shaw