Following the source of this bubble storm, it turns out it was this guy who collects bubble guns. I ended up having a chat with him about his hobby. He has several battery powered toys that create constant streams of bubbles. Some of his guns have been modified to accept another battery (or two?) for a higher rate of 'firing'. He really was filling up this reasonably large amphitheater with bubbles. Apparently it only works that well if the wind is 'right' and if he is firing with the wind.At first I thought it was a pretty weird hobby, but the more I think about it the awesomer it is. It was actually quite a sight to see that many bubbles, it did inspire me to do a bit of drawing and quite a few kids at the bottom started to go nuts when they realized that they were in the middle of this bubble storm.