Students were treated to an iridescent display of pastel colours this morning with the rare appearance of Polar stratospheric clouds, also known as nacreous clouds. These clouds are formed in the stratosphere at altitudes of between 15km to 25km. Due to their high altitude and the curvature of the surface of the Earth, these clouds receive sunlight from below the horizon and reflect it to the ground, shining brightly at dawn or dusk. The colours are displayed by crystals formed at approximately -80 degrees celsius, which happens more frequently in the Antarctic than the Arctic and is said to be indicative of ozone depletion.
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