What Are Undulatus Asperitas Clouds?

Undulatus asperitas clouds are a relatively new cloud type, officially recognized by the World Meteorological Organization in 2015 as the first distinct cloud type in over five decades. Initially proposed in 2008 by the Cloud Appreciation Society, these clouds are stratocumulus formations found at low to mid-level altitudes, typically from three to four kilometers above ground.

While asperitas clouds do not always signal impending rain, they often emerge in conjunction with showers and thunderstorms. In the case of this past Sunday, the clouds were a part of the atmospheric drama as a cold front swept through the Ottawa Valley, creating ideal conditions for this striking cloud type.

What Causes These Beautiful Clouds?

Geoff Coulson notes that there remains some mystery surrounding the precise formation of asperitas clouds. Meteorologists believe that they result from 'pockets' of rising and sinking air, coupled with rapid shifts in wind direction, known as wind shear. The interaction of these elements creates a visually stunning—and often chaotic—sky, as was the case in Ottawa that evening.

The cold front that moved through the region created a highly unstable atmosphere, contributing to the rise and fall of air masses that gives asperitas clouds their dramatic appearance. “We had all the ingredients for a pretty dramatic sky,” Coulson said.

Will We See Them Again?

Given their unique formation requirements, asperitas clouds are not commonly seen. Coulson mentioned that while this week is expected to bring cooler, quieter weather to Ottawa, the rare phenomenon may not make a repeat appearance in the immediate forecast.

Is Climate Change Involved?

Interestingly, while climate change is a hot topic in weather discussions, Coulson states that there is currently no evidence linking the occurrence of asperitas clouds directly to climate change. The exact conditions needed for their formation remain somewhat elusive, leaving meteorologists uncertain if they will become more frequent in the future.

A Storm Chaser's Perspective

Connor Mockett, a passionate storm chaser from eastern Ontario, pursued the thunderstorm that sparked this cloudy spectacle. Reporting from the field, he noted the transition from a shelf cloud to the emergence of asperitas clouds as he followed the storm through various locations. “I’ve never seen aspiratus like that in my life. It was the best display of clouds I have ever witnessed,” he exclaimed, urging residents of Ottawa to gaze upward before the moment passed.

So, for those who caught a glimpse of the sky over Ottawa that Sunday, it was undoubtedly a rare and breathtaking display—a reminder that nature can often surprise and delight us with its extraordinary phenomena. Whether you're a weather enthusiast or just someone who appreciates nature's beauty, the Undulatus asperitas clouds were a sight to behold. Don’t miss out the next time the skies surprise us!