Asperitas Clouds Grace Ottawa’s Skies

A rare atmospheric phenomenon captured the attention of Ottawa residents on the evening of October 6, 2024, as unusual cloud formations appeared over the city’s skies. Known as asperitas clouds, these formations are characterized by their distinctive, wave-like appearance, resembling undulating ripples.

First proposed and identified by the Cloud Appreciation Society in 2008, asperitas clouds gained recognition from the World Meteorological Organization (WMO) when they were added to its International Cloud Atlas in 2015. This marked the first new cloud type to be included in the atlas in over half a century. The term ‘asperitas’ is derived from the Latin word for ‘roughness.’

The precise formation mechanisms of asperitas clouds remain uncertain. However, meteorologists suggest that they are likely formed through the interaction of cooler, sinking air pockets with winds that shift direction from the upper to the lower parts of the cloud. This interaction potentially results in the clouds’ unique wave-like structure.

As these rare clouds graced the capital city, residents and visitors captured the stunning natural display, with many sharing their photographs on social media and with local news outlets such as CTV News Ottawa. The phenomenon has sparked both scientific curiosity and artistic interest among onlookers.