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Rainbow clouds delight Vancouver Island sky watchers

Cloud iridescence depends on the cloud’s moisture and how the sun hits it at a particular moment in time.
Bill Katz captured this photo of a rainbow cloud on Saturday over the Saanich Peninsula. Meteorologists say the phenomenon is created by small water droplets or ice crystals in the cloud refracting sunlight.

Colourful clouds sparkling with colours were real eye-catchers for anyone looking skyward around Southern Vancouver Island last week.

Bill Katz caught the natural phenomenon of cloud iridescence — sometimes called rainbow clouds — on the Saanich Peninsula on Saturday.

And dozens more posted their own images of the natural light show on social media, with some photos showing clouds resembling jellyfish with tentacles dripping colour.

Cloud iridescence happens in altocumulus, cirrocumulus, lenticular and cirrus clouds because of diffraction with sunlight. The phenomenon occurs when small water droplets or ice crystals scatter the sun’s light, according to meteorologists.

Brian Proctor of Environment Canada said it’s a relatively rare occurrence, though it can be common given the right conditions, all of which came together in the skies above the Island over the weekend.

He said it all has to do with the cloud’s moisture and how the sun hits it at a particular moment in time.

It usually occurs in a “thin cloud deck,” said Proctor, and can happen with high and low cloud activity. The wispy thin clouds are just forming and have super-cooled water droplets or ice crystals of about the same size.

The sun’s rays hit a few droplets at at time, creating a rainbow effect.

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