Rare Fallstreak Hole in Clouds: Freaky Phenomenon Often Mistaken for UFOs

Summary: A fallstreak hole occurs in clouds as a freaky, rare weather phenomenon. A fallstreak hole occurred in February 2015 over British Columbia.

view of fallstreak holes from above (top) and from below, in Arcadiana, southern Louisiana, on January 29, 2007: Jeff Schmaltz/NASA Goddard Space Flight Center, Public Domain, via NASA Earth Observatory

Fallstreak hole refers to an unusual weather phenomenon in which gaps or holes develop at 20,000 feet (6,096 meters) above the ground.

Fallstreak holes appear in two types of clouds. Altocumulus, or middle-altitude, clouds occur at altitudes of 6,500 to 20,000 feet (1,981 to 6,096 meters) and form as layers and patches of dark, large globular masses. The second type, cirrocumulus, or high-altitude, clouds, develop at altitudes above 20,000 feet (6,096 meters) and appear as patches, ripples and tufts of small, white cloudlets, often organized into rows.

Fallstreak holes enjoy such other picturesque common names as canal cloud, cloud hole, crop circle cloud, hole punch cloud, punch hole cloud, sky holes, skypunch and UFO cloud.

Fallstreak holes are considered to be rarities and are not specific to any geographical location on Earth. Famous sightings have occurred across the globe in widely separated locations. In Central Europe, a fallstreak hole was observed south of Linz in north central Austria in August 2008. In Eastern Europe, a fallstreak hole formed over Moscow in northeastern Russia in August 2008. In Oceania, a fallstreak hole occurred over Melbourne in eastern Victoria state on Australia's southeastern coast in November 2014. In the southeastern United States, a fallstreak hole was seen over Jay in the Panhandle of northwestern Florida in December 2007.

A recent fallstreak hole has made two spectacular appearances over southern British Columbia, Canada's westernmost province. The rare phenomenon premiered Sunday, Feb. 22, 2015. An even rarer encore occurred the following day, Monday, Feb. 23.

Despite presenting a strange beauty reminiscent of other worlds and of science fiction and oftentimes suffering associations with aliens and UFOs (unidentified flying objects), fallstreak holes are not unsolved mysteries for meteorologists, scientists who study meteorological phenomena. Meteorologists aim to expand knowledge and understanding of the Earth's atmosphere and to refine the process of weather forecasting through the dual application of science and technology.

For its generation, the fantastic phenomenon of fallstreak hole requires supercooled clouds, with water droplets in liquid state despite below-freezing temperatures, and atmospheric disruption, usually in the form of air traffic. Supercooled droplets remain in their liquid state even at temperatures below water's normal freezing point of 32 degrees Fahrenheit (zero degrees Celsius) because of a lack of ice nucleation particles, which are essential for transition into crystallization, water's solid state.

Airplanes may trigger crystallization through contact between exhaust particles and supercooled water droplets. Large ice crystals formed in the wake of air traffic create the fallstreak hole as they drop from the cloud deck. Depending upon atmospheric conditions, the ice crystals may fall to the Earth's surface as rain or snow or may evaporate, forming water's gaseous phase as water vapor, also known as aqueous vapor.

Fallstreak holes exemplify weather phenomena of rare occurrence and with often awe-inspiring, fantastic appearances. Fortunately, these strange formations have fairly simple origins delineated by acceptable scientific explanations. The science, however, serves as the backdrop for the visible spectacle that rewards skygazers with its stunning rarity.

Fallstreak holes belong to the wish list of hoped-for sightings that skygazers may feel particularly blessed to view even once in a lifetime.

rare hole-punch clouds in skies over Washington and British Columbia, February 2015: Jonathan Fox/NWS, CC BY 2.0, via StormHour @ StormHour/Twitter

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

view of fallstreak holes from above (top) and from below, in Arcadiana, southern Louisiana, on Jan. 29, 2007 ~ image by Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center: NASA Earth Observatory, Public Domain, via http://earthobservatory.nasa.gov/IOTD/view.php?id=7362

rare hole-punch clouds over Washington and British Columbia, CC BY 2.0, via StormHour @ StormHour/Twitter, @ https://twitter.com/StormHour/status/571301763921395712

For further information:

NWS Spokane, WA. "More Hole Punch or fallstreak hole clouds...over British Columbia." YouTube. Feb. 23, 2015.
Available @ https://www.youtube.com/watch?v=eeVGik_r5os&feature=youtu.be