Did you see it happen? On Tuesday, December 29th, multiple photos came in showing an interesting sight in the sky: a nearly-circular hole in the cloud deck.
(Kelsey Bass Meadville, MS)
This phenomenon, called a Fallstreak Hole or a Hole Punch Cloud, isn't exactly a rare thing to see, but it is somewhat uncommon.
So how did it form?
Yesterday, the layer of clouds was fairly high up in the sky yesterday morning. The temperatures at that level were below freezing, but the clouds were made up of liquid water droplets.
(Photo by Facebook viewer B.J. N Misty Lowery)
Did you know that water can be liquid well below freezing? It can stay liquid up to -40 degrees C! The catch is that as soon as the pure liquid touches anything solid (a speck of dust, a particle from an exhaust pipe, etc.) it will freeze.
In this case, an area in the cloud started to form ice crystals, likely because an airplane flew through the cloud and disturbed it. The flow of the air around the airplane may have been enough to disturb the balance in the cloud, and cause the temperature to get cold enough for ice crystals to start forming, even without anything to freeze to. The clouds made up of ice crystals give the hole punch that wispy, paintbrush look in the center.
(Photo by Pamela Cook Hopkins, taken at the SMRMC)
The ice crystals now act as that little bit of something solid for water to freeze to. In fact, the water vapor in the cloud (water in it's gaseous state) finds it much easier to deposit directly as ice than to condense as liquid on a water droplet. As a result, the hole gets bigger and bigger in a circular form as the droplets get eaten away and the feathery ice crystal clouds in the center flourish!
Meteorologist Julia Weiden
Photo by Rusty Hillman, Mississippi River
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