Hole Punch Cloud
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HOLE PUNCH CLOUD
The hole punch cloud does not have a scientific name, but I have found that most sights refer to it as the Fallstreak hole.
A Fallstreak hole is also know as the hole punch cloud, punch hole cloud, sky punch, cloud canal, or cloud hole.
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- The altitude of a Fallstreak hole is around 7.5 miles and is a regular cloud.
- The cloud forms spontaneously and it can happen anywhere.
The altocumulus cloud layer is composed of small water droplets that are below freezing called supercooled water droplets. If ice crystals can form in the layer of supercooled droplets, they will grow
FUN FACTS
- Andrew Heymsfield and collaborators, have shown that an aircraft passing through these cloud layers can trigger the formation of the heavier ice crystals
- A hole punch cloud needs an aircraft to be able to form
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- For the hole to form, the droplets in the cloud layer need to be “supercooled”. This means that the clouds are at a temperature below 0˚ Celsius, but have yet to freeze
- The expansion of the air as it passes over aircraft wings and (for certain types of plane) over the blades of its propellers, causes it to cool.
- This momentary cooling can be enough to take the temperature down low enough for the droplets to start to freeze spontaneously
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- Even though there aren’t enough icing nuclei around for the droplets elsewhere to freeze
- If Ice crystals can form in the layer of supercooled droplets, they will grow. This is important because the Ice crystals fall to earth and then leave a circulary void in the blanket of clouds
