A striking cloud formation, known as asperitas, settled over Vancouver on November 8, Friday. The unusual type of cloud was first observed in 2006 in Cedar Rapids, Iowa, by an amateur cloud spotter. CBC science specialist Darius Mahdavi confirmed the asperitas cloud, saying, "I've only properly seen them once before….but these ones are even better."
These clouds (Asperitas) over Vancouver as the rain rolls in. pic.twitter.com/OSj00Ee9Ry
— Rebecca Bollwitt (@Miss604) November 9, 2024
Mahdavi added that the clouds appear dark and stormy, however they don't produce rain. Meteorologists don't know what causes an asperitas cloud to form, but there are theories and a sense for the kinds of situations they form in.
Spectacular asperitas clouds over Fort Walton Beach, Florida. These wave-shaped clouds don't produce rainfall, but have been linked to thunderstorms. 📽: Andrew Farnam pic.twitter.com/l3alrk2cDT
— Wonder of Science (@wonderofscience) October 29, 2024
The asperitas clouds or "roughness" clouds are mostly seen before or after storms, in a very unstable atmosphere and whenever there are significant changes in wind direction higher in the atmosphere.
This amazing timelapse of asperitas clouds looks like waves in the sky. 📽: Alex Schueth pic.twitter.com/ideJrLJGoc
— Wonder of Science (@wonderofscience) June 7, 2024
The rare cloud was added to the World Meteorological Association's International Cloud Atlas, where they were described as an intense, chaotic wave-like formation.
Looks Like 'The Surface Of A Choppy Sea'
About more than a decade ago, Gavin Edmund Pretor-Pinney argued that asperitas clouds should be considered a unique cloud formation. Edmund founded the Cloud Appreciation Society in 2005, which connects cloud spotters and shares information on clouds. He kept seeing one rare type of cloud crop up.
In an interview with CBC News, Pinney said, "They would come in every now and then from different places: Australia, from Greenland, from across the US, from Europe and here in the UK."
"It's like looking up at the surface of a turbulent, choppy sea from below," he added.
According to Pinney, Canada has one or two confirmed sightings of the clouds every year, primarily over Ontario.