I just saw the coolest thing...
You can't take a photo of this, or get it on video, and a sketch wouldn't work.
Our yard is full of and bordered by a wide range of trees and bushes of different heights, shapes and shades of green, all crowded together. It makes quite a surface, so to speak.
Just now a flock of geese flew over, out of sight, not honking. All I saw was a sudden flowing of shadows rising and falling and rolling across all those different tree-leaf surfaces. It was dancing shadows across the side of the yard, seen from the window. Dappling, but nicely spaced out and moving steadily. I could see the flappings, wings and bodies on the shrubbery, from high up to low near the ground. It went on gently for about 10 seconds then I started seeing them actually in the blue sky as they flew over low. The sun was behind them so their shadows preceded them.