Fallstreaks spotted in the San Antonio sky Thursday

These “hole punch” clouds are formed from the rapid freezing of very cold water droplets

If you were running errands or went out to grab lunch on Thursday, you may have noticed a few “hole punch” clouds in the San Antonio sky.

This cloud phenomenon is called a fallstreak” and has to do with the process of freezing already very cold water droplets.

Here’s an explanation of how these fallstreaks are formed:

Believe it or not, there is a space for liquid water droplets to exist in temperatures at or just below 32° without actually freezing into ice crystals. Meteorologists call this supercooled water.

Often when an airplane flies through a cloud deck consisting of supercooled water droplets (the one over the San Antonio area today was situated at about 22,000 feet), the exhaust can introduce condensation nuclei, which are tiny particles that can kick-start the freezing process into ice crystals.

Once the water droplets freeze, they grow and start to fall, forming a hole. That hole then grows as droplets around it start to freeze and fall as well.

Have a photo or video of these fallstreaks? We’d love to see them! You can upload them to KSAT Connect here, and we may share them on air! You can also check out pictures other viewers have submitted.


About the Author

Meteorologist Mia Montgomery joined the KSAT Weather Authority Team in September 2022. As a Floresville native, Mia grew up in the San Antonio area and always knew that she wanted to return home. She previously worked as a meteorologist at KBTX in Bryan-College Station and is a fourth-generation Aggie.

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