On Monday, our friends down under were treated to a magnificent example of what’s known as a fallstreak cloud, sometimes referred to as a hole punch cloud. It earned this latter name because it looks like something literally punched a hole in the sky, leaving a large, round void surrounded by a milky white layer of clouds.
Posted to YouTube by JasonPrekop
Michael Efron, a forecaster with Australia’s Bureau of Meteorology, offered this concise explanation of how these cloud formations develop, via The Age:
They form when the water temperature in the cloud is below freezing, but the water has not yet frozen due to a lack of ice nucleation particles. When the water does start to freeze, it falls down to the surface … so you’re left with this cloud surrounding it, this clear area.
Eyewitnesses all around the Australian state of Victoria took in the stunning sky formation, which was extra special due to the appearance of a sun dog streaking across the middle of it.
Post by Meteo Europe.
Occasionally, we see examples of these in Washington, D.C. area, but it’s been a while. The last case I can recall was about a year ago, when photographers around the region captured a fallstreak cloud at sunset.
Here’s a terrific collection of fallstreak cloud photos from the Australia sighting, via Twitter and Instagram:
Just got this sent in from Geocaching Melbourne. Did you see the weird rainbow thing in the sky over Wonthaggi? pic.twitter.com/RGWLAUJpwM
— hit Gippsland (@hitgippsland) November 3, 2014
