On Saturday, December 14, an incredibly mysterious cloud bubbled out of the atmosphere along British Columbia’s west coast, just hours after a departing windstorm.
Its UFO-like shape captivated those who saw it. But, as strange as it looked, the science behind this mesmerizing formation reveals how it came to be.
Earl-s Cove mysterious cloud – Andrew Leyden – Submitted
The atmospheric ingredients
1. Varying winds with height
Atmospheric winds rapidly increase with height, changing directions as you move upward. This wind shear helped sculpt the cloud into its elongated shape, stretching it vertically into a striking, towering structure.
2. Moisture and lift
The low levels of the atmosphere surrounding the Comox Valley area were rich in moisture. Upper-air soundings from the time revealed strong upward motion (negative omega) in the mid-levels. This organized lift, combined with ample moisture and possible terrain forcing from eastern Vancouver Island, provided the energy needed for the cloud to grow and form its sculpted shape.
3. Turbulent features
Look closely at the cloud’s edges, and you’ll see sharp curls and undulations, a key signal of atmospheric turbulence. These features are often associated with mountain wave clouds or rotor clouds caused by air interacting with terrain.
Gibsons mysterious cloud – Stephen Gration
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The key to the cloud’s beauty
A dry layer aloft
High above the surface, a drier layer in the atmosphere set the stage for something extraordinary. As rising air mixed with the dry air aloft, evaporative cooling likely sharpened the cloud’s edges and enhanced instability.
Conditional Instability
The atmosphere was conditionally unstable, meaning cooler air aloft fostered vertical cloud growth—especially when lift was available from the weakening low pressure.
Lighting magic
Comox mysterious cloud – Deneice Slyuma
While science explains the cloud’s formation, evening light played a crucial role in its visual appeal and helped it go viral on social media. The low-angle sunlight cast dramatic contrasts, highlighting the cloud’s intricate features and giving it an “out-of-this-world” glow.
The deep low that was moving inland added an extra boost. This frontal ascent—lift caused by the frontal system’s motion—helped the cloud blossom even more dramatically.
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This cloud appears to be a hybrid formation, blending some characteristics of towering cumulus clouds with laminar, wave-like features typically seen in mountain wave clouds.
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Parts of this cloud even resemble a lenticular cloud–smooth, lens-like features formed by air flowing over Vancouver Island mountain ranges.
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While strong lift and conditional instability allowed the cloud to grow vertically like a towering cumulus, terrain-induced waves and high wind shear sculpted its edges into smooth, undulating forms.
This convergence of factors—a mix of orographic lift, wind shear, and lingering ascent from the windstorm—created a truly one-of-a-kind cloud structure. It’s a stunning reminder that even the weirdest, most photogenic clouds can be explained by atmospheric science—though they’ll always retain a bit of magic when captured in the perfect light.
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Header image credit: Stephen Gration