Helical Clouds

March 12, 2021


Photographer: Nelson Reticence
Summary Authors: Nelson Reticence; Jim Foster

These eye-catching clouds were observed over Holyoke, Massachusetts, at sunset on November 24, 2020. Looking like helical DNA strands or breaking waves, they form where the layer of air that contains the clouds moves at a different velocity and has a different density than the air in the layer just above the clouds. This results in air flows that tend to have a distinct serpentine motion.