Years ago, I came across the autobiography of a prominent former Nazi in a bookstore. His name escapes me at the moment but I think the was an architect who'd been in charge of wartime production (Milch?). In the book, he had a picture of one of the big Nuremberg party rallies where he trained spotlights up in the air like that. It was a very dramatic picture.

This proposal is a much more benign idea and is beautiful. I wouldn't use lasers because if they're powerful enough to be readily visible, they could be dangerous to people's eyes should they reflect from clouds. Directed spotlights would provide the desired effects.