Fallstreak hole
A Fallstreak hole is a large circular or elliptical gap that can appear in cirrocumulus or altocumulus 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 ice nucleation.
Snow roller
A snow roller is a rare meteorological phenomenon in which large rolls of snow are formed naturally. The snow is blown by the wind collecting material along the way, almost the same way in which large snowballs are formed.
