Mother Of Pearl Clouds

Nacreous clouds, sometimes called mother-of-pearl clouds, are rare but once seen are never forgotten. They are mostly visible within two hours after sunset or before dawn when they blaze unbelievably bright with vivid and slowly shifting iridescent colours.

They are filmy sheets slowly curling and uncurling, stretching and contracting in the semi-dark sky. Compared with dark scudding low altitude clouds that might be present, nacreous clouds stand majestically in almost the same place - an indicator of their great height.

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By Brillern

Elverum, Norway

They are wave clouds and their undulating sheet-like forms reveal the winds and waves of the stratosphere.

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Due to their high altitude and the curvature of the surface of the Earth, these clouds will receive sunlight from below the horizon and reflect it to the ground, shining brightly well before dawn or after dusk.

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By Alan Light from Charlotte, USA

Nacreous clouds over the NASA Radome, McMurdo Station, Antarctica

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By François Guerraz

A stratiform type I PSC (white cloud above the orange tropospheric clouds), showing fine horizontal structures in the veil

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my favourite kind