Punch Hole Clouds may appear as a circular or oval holes in a layer of supercooled clouds; sometimes they assume a form of a perfect circle and persist for quite a long time, drifting together with the cloud layer. One explanation seems to blame the air traffic (the jet contrail intersections) combined with a thermal inversion (a circular motion of a rising warm air). Here is one, observed over the Gunnison Valley in Colorado:
Another strange hole in the cloud, reported from Mobile, Alabama USA, Dec. 2003 (and covered by BBC News):
Photo taken in Melbourne, Australia in 2003:
It seems both rising and sinking air currents can create the same effect. Sometimes a very stable, uniform layer of high-altitude clouds can get "punched though" by a pocket of cold air, which sinks toward the ground - creating the circular hole formation.
These "cloud holes" can look like the footprints of some celestial being (UFO enthusiasts rejoice!) or can be amazingly round, like this pair observed in Gallatin, Tennessee by Wayne Carter:
NASA takes satellite images of this phenomenon
NASA Terra satellite equipped with the Moderate Resolution Imaging Spectroradiometer (MODIS) has captured these images over Acadiana area in southern Louisiana - a splattering of round holes actually stretched over several states: Oklahoma, Arkansas, Louisiana, and Texas. Some were elongated, some appeared to have smaller clouds inside them.
Cloud Vortices: another "holey" sky phenomena
Theodore von Karman's "Cloud Vortices" are something else, again: they form when the wind encounters a barrier - such as the Aleutian islands, in this case - and the flowing eddies of cloud create a weird pattern. The image you see below was photographed from the International Space Station, and the animation shows the double row of vortices, which rotate opposite from each other.
More Incredible and Fascinating Clouds
