A mysterious hole in the sky appeared over Białystok on Sunday morning. We received a photo of it on Kontakt24. The phenomenon is called cavum.
Clouds with an oval hole in the middle. An unusual phenomenon called cavum was observed on Sunday over Białystok Reporter24 Szymon Dykiert.
“In the morning hours I observed a cavum phenomenon, which lasted about 30 minutes, then disappeared. Although it was not very spectacular, it still caught my attention,” wrote Reporter24.
The phenomenon of cavum
The cavum phenomenon occurs rarely. It is a well-defined, usually round hole in a thin layer of strongly supercooled cloud of the middle or high level. From the inside of the so-called hole falls virga (precipitation that does not reach the ground) or cirrus cloud in the form of fibrous wisps. This phenomenon occurs when there are no rapid movements in the atmosphere and the air is clean, and the temperature drops very low.
“Cavum viewed directly below it is most often circular, but from a greater distance it takes on an oval shape, and with time it increases in size,” we read in the study “New Cloud Classification”, published in 2017.
Main image source: Szymon Dykiert/Kontakt24