Parts of Alberta treated to 'night-shining clouds,' the rarest cloud type
Noctilucent clouds are one of the rarest cloud formation and they form on the edge of space
Parts of Alberta witnessed a spectacle early Friday morning as rare noctilucent clouds, also known as night-shining clouds, lit up the sky.
These unique clouds are only visible on summer nights in specific regions of the world, adding to their rarity.
Noctilucent clouds form in the mesosphere, located 50-85 km above Earth's surface. This layer lies far above where daily weather develops in the troposphere and even beyond the stratosphere where the ozone layer resides.
The mesosphere contains extremely little water vapour — about one one-hundredth of the amount found in Sahara Desert air, according to NASA.
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To form these clouds, temperatures must plunge to around -120°C. The mesosphere, which becomes coldest during the summer months, allows the tiny amount of water vapour to condense onto particles of cosmic dust. This process creates very thin, wispy clouds that require a dark night sky to be visible.
These clouds only appear between latitudes of approximately 50° and 70°, which includes most of Canada.
However, they are not visible in the Arctic Circle during summer, as 24 hours of daylight obscure the night sky.
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For those lucky enough to catch a glimpse, noctilucent clouds offer a striking reminder of the atmospheric wonders beyond our daily weather.