It’s no wonder that people have mistaken them for flying saucers or other unusual phenomenon. They don’t look like your average cloud. Alien Spaceship Shaped Hole in clouds form when airplanes fly through banks of mid-level altocumulus clouds — clouds made of supercooled droplets.
The features are officially called cavum clouds, but are sometimes nicknamed hole-punch clouds or fallstreak holes. They’re so big that you can see them from the ground and in space.