Wednesday, November 26, 2014

Fallstreak Clouds: Nature's Rapture

Fallstreak Cloud over Australia (November, 2014)

At the beginning of the month, a rather peculiar anomaly was spotted over the skies of Wonthaggi, Australia.  Dozens took to Twitter to share photographs and offer up theories as to what this strange thing in the clouds was.  Many thought that it may be extra-terrestrial in nature...possibly some type of alien spaceship with a shoddy cloaking mechanism engaged.  Some described the image as what the sky will look like during the Rapture.  Others simply had no idea what this thing could be.

Luckily, science had the answer.

This weird anomaly goes by many names including punch hole cloud, hole punch cloud, and fallstreak...and its a MOSTLY natural phenomenon. According to Wikipedia, "such holes are formed when the water temperature in the clouds is below freezing but the water has not frozen yet due to the lack of ice nucleation particles.  When ice crystals DO form, it will set off a domino effect, due to the Bergeron Effect, causing the water droplets around the crystals to evaporate: this leaves a large, often circular, hole in the cloud."

Interestingly, fallstreak holes were not observed prior to World War II, which led to a working theory that these anomalies are actually sparked by airplanes!  In a study led by Andrew Heymsfield, "the research determined that precipitation is triggered by water droplets at extremely cold temperatures, below about 5 degrees. As the air is cooled behind the planes, the water droplets freeze and drop toward Earth."

Still...these are beautiful...and beautifully creepy!  They've certainly fooled many a person as to their true identity and will probably continue to do so for years to come!

10 Examples of Fallstreak Clouds
Fallstreak in Australia
USA Today Article

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