Hole-Punch Cloud

A fallstreak hole, also known as a punch hole cloud, is a large circular or elliptical gap, that can appear in cirrocumulous or altocumulous clouds. Such holes are formed when the water temperature in the clouds is below freezing but the water has not frozen yet due to the lack of icenucleation particles. When ice crystals do form it will set off a domino effect, due to the Bergeon process, causing the water droplets around the crystals to evaporate: this leaves a large, often circular, hole in the cloud.