Tag Archives: Optics


ˈneɪkriːəs nacreous: pertaining to or resembling mother-of-pearl Nacreous clouds are in the UK news at present, with multiple sightings in Scotland. There was an interesting divide in the BBC news coverage of the phenomenon this evening, with national newsreader George Alagiah intoning some twaddle about “forming at sunset” and “caused by refraction” in a sing-song … Continue reading Nacreous