Several strange holes were spotted in the clouds Tuesday morning by Global News viewers.
They’re called fallstreak holes, and it’s not the first we’ve seen them over the South Coast — nor will it be the last.
These holes form in certain types of clouds, altocumulus or cirrostratus, and on Tuesday we had both over the region.
The holes are created when a portion of the water in the cloud layer has dropped below freezing but hasn’t yet frozen into ice crystals. This water is said to be in a supercooled state.
The reason it hasn’t frozen is a lack of “ice nuclei”: tiny particles onto which ice crystals can begin to form.
But once just one ice crystal forms, a domino effect called the Bergeron Process takes place, and all of the supercooled droplets freeze quickly.
These ice crystals then fall, creating the wispy part of the fallstreak hole. But they aren’t able to fall very far, instead melting and evaporating quite quickly.
The hole is formed by both the loss of water in the cloud by ice crystals falling and another result of the Bergeron Process which causes the rest of the water in the cloud to evaporate.
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