Rare formations · feature
Fallstreak holes
A window punched through cloud
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Alan Bilinsky
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Full credit
Own work
Displayed at reduced resolution. See the original file for full licensing information.
Full credit
Own work
Displayed at reduced resolution. See the original file for full licensing information.
Swipe or scroll sideways to explore the photographs. Photos may include other cloud types; names and credits come from their source records.
Spot it
A distinct hole or channel, often containing falling wisps.
How it forms
Ice growth and falling crystals open a gap in a supercooled droplet layer.
Read the sky
The hole is a local cloud process, not a signal that a storm must follow.
Where to look
Look in thin supercooled cloud layers; aircraft can sometimes trigger the process.
Little sky facts
Reveal fact 1
The formal name is cavum.
Reveal fact 2
The hole may be circular or stretched out.
Reveal fact 3
A fallstreak can remain inside the opening.
Reveal fact 4
Liquid cloud droplets can exist below freezing.
Try this
Draw the hole as a portal with an icy curtain.
Draw your own cloud ↗Read a little deeper
Met Office · formation and weather
Conditions described here are places to look, not a global frequency ranking. Use local weather forecasts and warnings for decisions. Never look directly at the Sun.