Several YNU members reported seeing beautiful 'mother of pearl' clouds over various parts of Yorkshire on the 1st and 2nd February. These nacreous clouds are a rare phenomenon, formed in the lower stratosphere at around 70,000 feet at temperatures of around -78C. The iridescent colours are caused by ice crystals refracting the sun's rays. Although beautiful, these clouds are actually damaging to the ozone layer as they catalyse reactions between ozone and chlorine which has been introduced into the atmosphere by substances such as chlorofluorocarbons (CFCs).
Thanks to YNU members Barry Warrington and Phil Lightfoot for providing photographs.
(13th February 2016)