This winter sky over Bristow, Virginia, US reminded Edward Callaway (Member 44,902) of a thin, shimmering, gauzy textile, and it seemed to fall apart as he watched.

This lacelike formation is known as lacunosus, which means ‘having holes’ in Latin. It is a pattern that is found in several of the ten main cloud types, and it occurs where cool air above sinks down in pockets through a layer of cloud. In this case, the mid-level cloud Altocumulus was gently teased apart by such localised downdrafts. They perforated the layer with holes that would have gradually grown like a fraying sky fabric. The striking effect only lasts for a few minutes, making lacunosus a rare cloud to spot.