Tag Archives: nacreous cloud

Another gorgeous shot of the ‘Mother of Pearl’ or nacreous cloud formations which occurred late last year over Sweden, in this case, on New Year’s Eve in the skies above Ostersund. To wit:

A relatively rare phenomenon in clouds known as iridescence can bring up unusual colours vividly or even a whole spectrum of colours simultaneously. These polar stratospheric clouds clouds (…) are formed of small water droplets of nearly uniform size. When the Sun is in the right position and, typically, hidden from direct view, these thin clouds can be seen significantly diffracting sunlight in a nearly coherent manner, with different colors being deflected by different amounts. Therefore, different colours will come to the observer from slightly different directions. Many clouds start with uniform regions that could show iridescence but quickly become too thick, too mixed, or too angularly far from the Sun to exhibit striking colours. 

(Image: Goran Strand)

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Behold: vivid iridescent nacreous or ‘mother of pearl’ clouds over Tandalen in Sweden late last week. To wit:

 …they are rare. This northern winter season they have been making unforgettable appearances at high latitudes, though. A type of polar stratospheric cloud, they form when unusually cold temperatures in the usually cloudless lower stratosphere form ice crystals. Still sunlit at altitudes of around 15 to 25 kilometers the clouds can diffract sunlight after sunset and before the dawn.

Image: P-M Hedén (Clear Skies, TWAN)

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