In the spring of 2009, researchers on the Second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) field project set out across the Great Plains to study tornadoes, but that’s not the only phenomenon they observed.

Turboprop and jet aircraft can create hole-punch clouds, which have long fascinated the public.

They’ve been called “crop circles in the sky.” Across the world, sightings of oddly circular holes within cloud layers—dubbed hole-punch clouds by scientists—have triggered bemusement and speculation.

Cirrus clouds—thin strands or sheets usually composed of ice crystals—form high in the atmosphere. A new study led by NCAR scientist Steve Massie employs satellite technology to observe the clouds in greater detail than before.