What Did You See? HOLE IN THE SKY
Back in February of 2015, I noticed a series of strange holes that would appear in cloud layers above my house. I took several pictures of this phenomenon and after a bit of research and the help of a friend, I found out what these holes actually are. They are called a fall streak hole, or hole punch clouds.
Cavum (cloud) A cavum (also known as a fallstreak hole, 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. 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 Bergeron process, causing the water droplets around the crystals to evaporate: this leaves a large, often circular, hole in the cloud.
It is believed 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- 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, grow quickly by the Bergeron process, causing the droplets to evaporate and creating a hole with brush-like streaks of ice crystals below it. The articles by Westbrook and Davies (2010) and Heymsfield et al. (2010)  explain the process in more 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.
- Check Out the Iridium-2 Launch Webcast - June 25, 2017
- Solar Eclipse Across America: Science, Yes, and So Much More! - June 24, 2017
- Playster Partners With Nelvana To Add Popular Kids’ TV Shows To Its Catalog - June 21, 2017
- Futurama: Worlds of Tomorrow Is Launching On June 29; Reveals New Animation Featuring Stephen Hawking, George Takei, Bill Nye, And Neil Degrasse Tyson - June 20, 2017
- Young Jamaican Actor Breaks Barriers, Opens Yacht Charter Company – Creates History - June 19, 2017
- E3 2017 WRAPS AFTER RECORD ATTENDANCE - June 17, 2017
- FLIGHT OF BOEING 787-10 AND 737-MAX 9 IN DRAMATIC DISPLAY - June 17, 2017
- ON THE HUNT FOR PORCH PIRATES - June 12, 2017
- Are UFOs Real? Ask Me, Please! - June 12, 2017
- Six Questions to Ask Your Insurance Agent - June 7, 2017