Truth or Hoax: Strange "Hole-Punch Clouds" Made By UFO?
Whereas many UFO enthusiasts think that the strange "hole-punch clouds" that looked like circular patches of clear sky, surrounded by clouds are "footprints" of hovering UFOs, science explained that these are atmospheric occurrence made by falling-ice crystals, which could originate in a higher cloud or made by any commercial jet aircraft passing by.
Scientifically, these hole-punch clouds are called fallstreak holes.
In 2004, a photo showing an incident of a fallstreak holes was sent to NASA. The photo was taken at the Botanical Gardens in Norfolk, VA by students of Mobile Alabama.
Explaining the incident, NASA said, it all starts with ice crystals that expand large enough to fall below as a fallstreak.
"If the air has just the right temperature and moisture content, the falling crystals will absorb water from the air and grow."
"The moisture lost from the air increases the evaporation rate from the cloud water droplets so they dissipate to form the hole. The now heavier ice crystals continue to fall and form the more tenuous wispy cloud-like virga seen inside and just below the hole. Water and ice from the virga evaporates before they reach the ground."
For the hole to form, the water must be so cold, as in "supercooled," (below zero degrees Celsius), and that there should be a surface to freeze on.
What is the role of the aircraft in the process? According to a study published in Science Magazine, the aircraft flying through the cloud can low down temperature enough to set off the freezing process.
Referring to the study, Weather.com reported that as explained by the researchers, the propeller and wings of aircraft passing through the cloud layers can set off the formation of the heavier ice crystals because it causes the air to expand and cool well below the original temperature.
Andrew Heymsfield of the National Center for Atmospheric Research, one of the authors of the study said his team found out that at lower altitudes, jets can punch holes in clouds and these holes can expand for hours.