Study Links Airplanes to Hole-Punch Cloud Phenomenon
Posted on June 14, 2010
Sightings of holes punched in clouds have triggered the public's interest for many years. A hole over Moscow generated numerous headlines in October, 2009. Here is a video of the Moscow hole in the sky.
A study, being published this month in the Bulletin of the American Meteorological Society, says these holes in the sky are caused by aircraft. The research found that as aircraft climb or descend under certain atmospheric conditions, they can inadvertently seed mid-level clouds and cause narrow bands of snow or rain to develop and fall to the ground. This seeding process can leave behind odd-shaped holes or channels in the clouds, which are known as hole-punch clouds. The study says the key ingredient for developing these holes in the clouds are water droplets at subfreezing temperatures, below about -15 degrees Celsius.
"Any time aircraft fly through these specific conditions, they are altering the clouds in a way that can result in enhanced precipitation nearby," says Andrew Heymsfield, a scientist with the National Center for Atmospheric Research (NCAR) and the lead author of the new study. "Just by flying an airplane through these clouds, you could produce as much precipitation as with seeding materials along the same path in the cloud."
Heymsfield says precipitation from planes may be particularly common in regions such as the Pacific Northwest and western Europe, because of the frequent occurrence of cloud layers with supercooled droplets.
You can read more about the new hole-punch cloud study here and here.