[BAA-ebulletin 00894] Nacreous clouds
BAA electronic bulletins service
baa-ebulletin at britastro.org
Mon Feb 1 22:49:46 GMT 2016
Nacreous clouds were seen from Cambridge this evening. This type of cloud is
fundamental to the creation of the ozone hole over Antarctica and is rarely
seen from the UK. The clouds form over the polar regions at heights of
around 10 to 20km. They are usually visible during civil twilight - the denser
cloud has beautiful pearly coloured margins and is quite bright, but there is
also a diffuse component that appears like stratocumulus cloud, but is much
higher.
This winter has seen an unusually cold Arctic stratosphere, and over the last
couple of days the "polar vortex" with the coldest air has become very
elongated and has reached down to the UK. There is a small chance that the
clouds might again be visible before sunrise on February 2, but after that the
area of cold air moves away from the UK.
Jonathan Shanklin
BAS Fellow
British Antarctic Survey, Madingley Road, Cambridge CB3 0ET, England
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