Those strange clouds over Vancouver are called ‘asperitas,’ and they are very rare [Video]

A striking cloud formation, known as asperitas, formed over Vancouver on Friday.

The rare type of cloud, whose name is Latin for “roughness,” was first observed in 2006 by an amateur cloudspotter in Cedar Rapids, Iowa.

CBC science specialist Darius Mahdavi confirmed the formation saying, “I’ve only properly seen them once before … but these ones are even better.”

Mahdavi said though the clouds look dark and stormy, they don’t produce rain.

Meteorologists don’t know exactly what causes an asperitas cloud to form, but there are theories and a sense for the kinds of circumstances they form in.

They are often seen before or after storms, in an unstable atmosphere with lots of updrafts and downdrafts, and whenever there are significant changes in wind direction higher in the atmosphere.

In 2017, they were added to the World Meteorological Association’s International Cloud Atlas, where they were described as an intense, chaotic wave-like formation.

Like ‘the surface …