By: Meteorologist Courtney Steimann
Updated: Feb 25th 2019

Courtney's Cloud Corner: Fallstreak Holes

Typically altocumulus and cirrocumulus clouds have a blanket effect over the sky, but if you’re lucky, you may see a fallstreak hole. Fallstreak holes or “hole punch clouds” appear exactly like their nickname describes. Like there was a hole punched through the blanket of clouds engulfing the sky. In this event, the said clouds contain supercooled liquid droplets that will only freeze once it forms ice nuclei (ice crystals), or if the air temperature surround it is below the frigid -40 Celsius. A good way for the supercooled liquid droplets to freeze would be if something punched through it like an airplane. This would enough to start the nucleation process of freezing the ice crystal. Once they freeze they begin to grow larger. Once large enough, they will drop lower than the existing cloud creating the famous fallstreak hole.


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A fallstreak hole within altocumulus clouds.
A fallstreak hole within altocumulus clouds.
Airplane within the clouds.
Airplanes can be a way to start the nucleation process into ice crystals.
Airplane within the clouds.
Fallstreak holes can be formed with the help of airplanes flying through the existing clouds.