Puzzled residents of Southern Finland gazing at the skies on Wednesday morning may have noticed a large, uncommon patch of blue in the middle of a thin mass of cloud. The phenomenon, known as a fallstreak hole or skypunch, gained immediate traction as users posted numerous images of the striking gap on social media.
Hole in the clouds: Rare skypunch forms over Southern Finland
Fallstreak holes are formed when supercooled water in the clouds reaches temperatures below 0 degrees Celsius, but does not freeze. Forming ice crystals cause water droplets around them to evaporate, causing a circular or elliptical hole. Aeroplanes passing through clouds have been known to cause cloud holes- writes yle.fi.
Yle meteorologist Seija Paasonen observed the momentary skypunch around 8 am.
"After about ten minutes, some thin, high clouds began to cover the gap. At about 8:20 am the hole was almost covered up," she says.
Paasonen estimates that the fallstreak hole occurred at an altitude of some 6-8 kilometres.
So-called holepunch clouds are not exactly uncommon, the meteorologist says, but still rare as the phenomenon only occurs a few times a year.
What made this hole special was its symmetrical, uniform shape.
"This is the most beautiful one I've ever seen," Paasonen says.
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