Rare clouds that glow in the dark are seen in upper US, Canada and Europe - Daily Mail

Noctilucent clouds were observed in parts of western US, Europe and Canada. The clouds consist of ice crystals that become visible when the sun is shining from blow the horizon.

The rarest clouds on Earth were spotted by sky watchers in parts of western US, Europe and Canada over the weekend a vibrant display that has not been seen in about 15 years. Known as noctilucent, t… [+4865 chars]

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