An unusual photograph of the sky above the Gulf of Mexico and off the coast of Florida was recently taken by NASA's Terra satellite. It showed some odd holes in the clouds. There have previously been reports of similar holes. In reality, these gaps have been confusing scientists for several decades. Some of them have even connected these formations to paranormal activity. However, research conducted over 13 years ago has revealed the mystery of these clouds, as per a report in Fox News.
The image taken last month by NASA's Terra satellite's Moderate Resolution Imaging Spectroradiometer (MODIS) displays a collection of elliptical or circular shapes that appear to have been carefully cut from the clouds. According to NASA, they even show "feathery wisps" near the centre of the hole.
These are referred to as cavum clouds, often dubbed fallstreak holes or hole-punch clouds. NASA claims that they are created by aircraft passing over banks of altocumulus clouds, citing research conducted by scientists at the University Corporation for Atmospheric Research (UCAR) and published in 2010 and 2011.
"Cavum clouds form when planes fly through banks of altocumulus clouds, mid-level clouds that have supercooled (below the freezing point of water but still liquid) water droplets. As air moves around the plane, a process called adiabatic expansion can make the droplets freeze into ice crystals! The ice crystals eventually grow heavy and fall out of the sky, leaving a hole in the cloud layer. In this image from NASA's Terra satellite, the falling ice crystals are visible in the centre of the holes as wispy trails of precipitation that never reach the ground - features called virga," NASA wrote in the caption.
UCAR researchers found that aircrafts, including big passenger jets, regional jets, private jets, military jets, and turboprops, could produce either cavum or canal clouds. Cavum clouds form when aircraft pass through at a relatively sharp angle, whereas canal clouds with long virga trails form when planes pass through at a longer, shallow angle.
