Fallstreak holes are enormous circular openings that appear in otherwise unbroken sheets of cloud. They often form when an aircraft passes through a layer of supercooled water droplets, causing them to freeze into ice crystals and fall. The reaction spreads outward, enlarging the opening, while a feathery column of ice remains suspended at its centre. By the time the portal becomes visible, the aircraft that made it has usually disappeared.
Fallstreak hole
