Pennsylvania sky displays rare hole-punch cloud phenomenon

A rare atmospheric phenomenon known as ‘hole-punch clouds’, ‘fallstreak holes’, or ‘cavum’ was recently observed in the skies over Pittsburgh, Pennsylvania. The phenomenon created large, circular, or oval gaps in the cloud layer, which initially led some observers to speculate about unidentified flying objects.

Scientific explanation indicates that these formations occur when an aircraft passes through a layer of clouds containing supercooled water droplets. Although these droplets remain liquid even below 0 degrees Celsius, they are highly unstable. The movement of an aircraft causes the air around its wings and body to expand and cool further, triggering the droplets to freeze into ice crystals. As these crystals grow and become heavy, they fall, leaving behind a visible hole in the cloud deck. This process can expand as surrounding droplets also freeze.