Explaining Hole-Punch Clouds

Researchers at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado have discovered how airplanes create hole-punch clouds when flying under specific atmospheric conditions and how their creation can temporarily change local weather conditions. These clouds – so called because of the odd holes found within their bodies – have been baffling scientists since they were first discovered in the 1940s.
 Hole-punch clouds seen over Texas, Lousiana, and Arkansas on January 29, 2007. These effects only occur in clouds at specific altitudes and temperatures, conditions frequently found in Western Europe and the Pacific Northwest of the United States. (Source: NASA Earth Observator/Jeff Schmaltz)
Hole-punch clouds seen over Texas, Lousiana, and Arkansas on January 29, 2007. These effects only occur in clouds at specific altitudes and temperatures, conditions frequently found in Western Europe and the Pacific Northwest of the United States. (Source: NASA Earth Observator/Jeff Schmaltz)

Ice physicist Andrew Heymsfield of NCAR began exploring the phenomenon of hole-punch clouds after accidentally causing an unexpected snowstorm while flying in a small research airplane in 2007. The plane was loaded with various instruments, including a series of cameras which captured a canal-like hole in the clouds. Another turboprop plane followed the same path shortly thereafter and five minutes after snow began to fall, dropping two inches of snow in 45 minutes over a 20 by 2.5 mile area beneath the affected clouds.

These hole-punch effects only occur in clouds at specific altitudes and temperatures, conditions frequently found in Western Europe and the Pacific Northwest of the United States. Such clouds are completely saturated with water, so much so that there are few particles and impurities to support ice condensation at normal air temperatures. The force of an airplane’s propeller or, to a lesser extent, a jet’s wings, cools the surrounding air, dropping temperatures sufficiently to initiate ice formation without the presence of the impurities. This effectively seeds the clouds with ice particles that attract nearby water vapor until it rains or snows. This precipitation effectively clears out all of the water vapor along the path flown, causing the holes that give these clouds their name.

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Heymsfield and his colleagues were able to take the data from their research flights and couple it with previous studies on aircraft-produced ice particles caused by turboprops to finally link the hole-punch clouds to airplanes and explain the local weather effects experienced when these clouds appear. Heymsfield plans to use satellite images to further study the effect of both turboprop and jet planes on clouds. As understanding of these effects increases, it may be possible to leverage this phenomenon to better control rainfall.

TFOT has previously reported on wind-powered cloud seeding yachts that increase the reflexivity of clouds. TFOT has also reported on other weather and climate topics including the rate of ecoshift necessary to keep up with current climate changes, the destructive power of hurricanes, and a hurricane machine capable of simulating a category 3 storm to help researchers study such storms.

Read more about how airplanes cause hole-punch clouds and local precipitation in this article from the UCAR Magazine published by the National Center for Atmospheric Research.