A fallstreak hole (also known as a cavum,[1]hole punch cloud, punch hole cloud, skypunch, cloud canal or cloud hole) is a large gap, usually circular or elliptical, that can appear in cirrocumulus or altocumulus clouds. The holes are caused by supercooled water in the clouds suddenly evaporating or freezing, and may be triggered by passing aircraft.
Such holes are formed when the water temperature in the clouds is below freezing, but the water, in a supercooled state, has not frozen yet due to the lack of ice nucleation. When ice crystals do form, a domino effect is set off due to the Wegener-Bergeron-Findeisen process, causing the water droplets around the crystals to evaporate; this leaves a large, often circular, hole in the cloud.[3] It is thought that the introduction of large numbers of tiny ice crystals into the cloud layer sets off this domino effect of fusion which creates the hole.
The ice crystals can be formed by passing aircraft, which often have a large reduction in pressure behind the wing-tip or propeller-tips. This cools the air very quickly, and can produce a ribbon of ice crystals trailing in the aircraft's wake. These ice crystals find themselves surrounded by droplets, and grow quickly by the Bergeron process, causing the droplets to evaporate and creating a hole with brush-like streaks of ice crystals below it. An early satellite documentation of elongated fallstreak holes over the Florida Panhandle that likely were induced by passing aircraft appeared in Corfidi and Brandli (1986).[4] Fallstreak holes are more routinely seen by the higher resolution satellites of today (e.g., see fourth example image in this article).
The articles by Westbrook and Davies (2010)[5] and Heymsfield et al. (2010)[6] explain the processes behind the formation of fallstreak holes in greater detail, and show some observations of their microphysics and dynamics. Such clouds are not unique to any one geographic area and have been photographed from many places.
^Sutherland, Scott (March 23, 2017). "Cloud Atlas leaps into 21st century with 12 new cloud types". The Weather Network. Pelmorex Media. Retrieved 24 March 2017.
^"'UFO cloud formation' filmed in Romania (subscription required)". www.telegraph.co.uk. 26 October 2009. Retrieved 13 October 2021.
^"Cloud Appreciation Society | Fallstreak Holes (February '06)". cloudappreciationsociety.org. 31 July 2006. Retrieved 2017-07-29.
^Westbrook, Chris; Davies, Owain (July 2010). "Observations of a glaciating hole-punch cloud". Weather. 65 (7): 176–180. arXiv:0907.4302. Bibcode:2010Wthr...65..176W. doi:10.1002/wea.504. S2CID 37383288.
^Heymsfield, Andrew J.; Kennedy, Patrick C.; Massie, Steve; Schmitt, Carl; Wang, Zhien; Haimov, Samuel; Rangno, Art (2010). "Aircraft-Induced Hole Punch and Canal Clouds: Inadvertent Cloud Seeding". Bulletin of the American Meteorological Society. 91 (6): 753–766. Bibcode:2010BAMS...91..753H. doi:10.1175/2009BAMs2905.1.
External linksedit
Wikimedia Commons has media related to Cavum (meteorology).
April 11, 2024
fallstreak, hole, fallstreak, hole, also, known, cavum, hole, punch, cloud, punch, hole, cloud, skypunch, cloud, canal, cloud, hole, large, usually, circular, elliptical, that, appear, cirrocumulus, altocumulus, clouds, holes, caused, supercooled, water, cloud. A fallstreak hole also known as a cavum 1 hole punch cloud punch hole cloud skypunch cloud canal or cloud hole is a large gap usually circular or elliptical that can appear in cirrocumulus or altocumulus clouds The holes are caused by supercooled water in the clouds suddenly evaporating or freezing and may be triggered by passing aircraft Fallstreak hole Cavum Fallstreak hole over AustriaAbbreviationcavGenusCirrocumulus Altocumulus StratocumulusVarietySupplementary featureAltitude500 15 000 m 2 000 49 000 ft AppearanceHole in the cloudsPrecipitationVirgaBecause of their rarity and unusual appearance fallstreak holes have been mistaken for or attributed to unidentified flying objects 2 Contents 1 Origin 2 Examples 3 See also 4 References 5 External linksOrigin editSuch holes are formed when the water temperature in the clouds is below freezing but the water in a supercooled state has not frozen yet due to the lack of ice nucleation When ice crystals do form a domino effect is set off due to the Wegener Bergeron Findeisen process causing the water droplets around the crystals to evaporate this leaves a large often circular hole in the cloud 3 It is thought that the introduction of large numbers of tiny ice crystals into the cloud layer sets off this domino effect of fusion which creates the hole The ice crystals can be formed by passing aircraft which often have a large reduction in pressure behind the wing tip or propeller tips This cools the air very quickly and can produce a ribbon of ice crystals trailing in the aircraft s wake These ice crystals find themselves surrounded by droplets and grow quickly by the Bergeron process causing the droplets to evaporate and creating a hole with brush like streaks of ice crystals below it An early satellite documentation of elongated fallstreak holes over the Florida Panhandle that likely were induced by passing aircraft appeared in Corfidi and Brandli 1986 4 Fallstreak holes are more routinely seen by the higher resolution satellites of today e g see fourth example image in this article The articles by Westbrook and Davies 2010 5 and Heymsfield et al 2010 6 explain the processes behind the formation of fallstreak holes in greater detail and show some observations of their microphysics and dynamics Such clouds are not unique to any one geographic area and have been photographed from many places Examples edit nbsp A fallstreak hole Leeds United Kingdom nbsp Elongated fallstreak hole over Bixby nbsp Fallstreak hole over Ann Arbor nbsp A fallstreak hole over Borso del Grappa Italy nbsp Fallstreak Holes over Ho okipa beach on Maui HawaiSee also editCircumhorizontal arc Cloud iridescence Distrails List of cloud types VirgaReferences edit Sutherland Scott March 23 2017 Cloud Atlas leaps into 21st century with 12 new cloud types The Weather Network Pelmorex Media Retrieved 24 March 2017 UFO cloud formation filmed in Romania subscription required www telegraph co uk 26 October 2009 Retrieved 13 October 2021 Cloud Appreciation Society Fallstreak Holes February 06 cloudappreciationsociety org 31 July 2006 Retrieved 2017 07 29 Corfidi Stephen Brandli Hank May 1986 GOES views aircraft distrails PDF National Weather Digest 11 37 39 Westbrook Chris Davies Owain July 2010 Observations of a glaciating hole punch cloud Weather 65 7 176 180 arXiv 0907 4302 Bibcode 2010Wthr 65 176W doi 10 1002 wea 504 S2CID 37383288 Heymsfield Andrew J Kennedy Patrick C Massie Steve Schmitt Carl Wang Zhien Haimov Samuel Rangno Art 2010 Aircraft Induced Hole Punch and Canal Clouds Inadvertent Cloud Seeding Bulletin of the American Meteorological Society 91 6 753 766 Bibcode 2010BAMS 91 753H doi 10 1175 2009BAMs2905 1 External links edit nbsp Wikimedia Commons has media related to Cavum meteorology Retrieved from https en wikipedia org w index php title Fallstreak hole amp oldid 1202415981, wikipedia, wiki, book, books, library,
