The crew at the McMurdo Station in Antarctica captured this beautiful example of nacreous (a.k.a. mother-of-pearl) clouds on 25 August 2013. (Jack Green / National Science Foundation)
Located in a coastal region at the southern tip of Ross Island – a scant 1,360 km north of the South Pole – is the main U.S. research centre in Antarctica. The McMurdo Station, which is now the largest community in Antarctica and the location of the only ATM on the continent, has been open since 1956. As such a frigid location, it boasts ideal conditions for the formation of nacreous clouds (also known as polar stratospheric clouds), such as those in the picture above. For obvious reasons, nacreous clouds are also often referred to as mother-of-pearl clouds.
They are most visible within two hours after sunset or before dawn, forming in the lower stratosphere (15-25km above the ground) at temperatures of around 85C. Their bright iridescent colours are result of their composition – similarly sized, fairly uniform ice crystals, about 10µm across.
As if the aurora borealis didn’t give you enough reason to bundle up and head to the poles.
Read more about McMurdo Station here, or research the phenomenon of nacreous clouds here.