A seldom seen phenomena occurred in the clouds above Minnesota Friday afternoon.
A ‘hole punch’ or ‘fall streak’ cloud was possibly picked up by visible satellite imagery. More details in the YouTube video:
These form when clouds high up in the atmosphere contain super-cooled water droplets that are well below freezing but still in liquid form. For the super-cooled droplets to freeze, they need a condensation nucleus, usually another ice crystal or dust, dirt, salt, etc..
This can come in the form of ice crystals from a passing airplane which leaves these behind in the form of contrails or it can come from higher clouds above this layer of clouds.
When the ice crystals fall into the super-cooled cloud, the droplets almost instantly freeze and fall through in the center. This creates a hole, and like a domino effect continues out from the center until it dissipates.