Rare cloud phenomenon - a cloud falling out of a cloud

Frank Terlouw and his son are fishermen who fish off the Mendocino Coast. They were out in their boat on the Pacific Ocean when they saw this unbelievably strange and beautiful cloud formation overhead. Frank later found an explanation for the rare phenomenon in an article by Victoria Tang in Earth Science magazine. An airplane can punch a hole in a cloud and actually change the weather below, causing that part of the cloud to snow. Frank never saw an airplane but the photo in the article was nearly identical to the one he took. With Frank's kind permission I've posted his fantastic photo below. Notice that in his photo Frank also captured a rainbow. Enjoy, enjoy!