Gewitter über Zwickau
https://commons.wikimedia.org/wiki/File:Lightning_cloud_to_cloud_%28aka%29.jpg
By André Karwath aka Aka (https://commons.wikimedia.org/wiki/User:Aka)
License: CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5/deed.en)