For decades, people speculated why strange gaps like this one, observed in 2008 over Linz, Austria, appeared in clouds. In 2010, researchers showed how airplanes might be responsible.
A Cool Discovery
This hole-punch cloud appeared in the sky over Mobile, Alabama, in 2003. Scientists believe that airplanes create these formations by cooling air and creating ice as they travel through clouds.
From a Distance
A NASA satellite captured this image of the holes and canals cut through cloud cover over Oklahoma, Arkansas, Louisiana, and Texas on January 29, 2007. This strange phenomenon resulted from a combination of cold temperatures, air traffic, and perhaps unusual atmospheric stability, according to NASA.
Clouds Louisiana Style
On Jan. 29, 2007, inhabitants of Acadiana, in southern Louisiana, saw unusual looking cloud formations called hole punch clouds. This strange phenomenon resulted from a combination of cold temperatures, air traffic, and perhaps unusual atmospheric stability, according to NASA Earth Observatory.
An Airplane's Fingerprint
Andrew Heymsfield of the National Center for Atmospheric Research and colleagues first documented a connection between these strange clouds and air traffic. In 2007, they flew a research plane through snow created after an airplane cut through clouds above Colorado.
An airplane can cause rain or snow to fall in its wake. This may reach the ground or evaporate on the way down.
If residents of rural West Virginia were to have looked up into the sky Dec. 11, 2009, they would have seen a halo of light bursting through the thin bank of clouds that hung overhead. The light was streaming through hole-punch clouds and canals, most likely created by passing airplanes. The strange cloud phenomenon was captured that day by NASA's Landsat-5 satellite.