Imaged 18th February by Adrian Smith in Yorkshire, England
The UK, The Netherlands, Germany and Scandinavia are experiencing a series of unusually bright and intensely colourful twilights.
Glorious twilights are sometimes caused by volcanic dust ejected into the stratosphere but this is unlikely to be the reason. Europe's cold anticyclonic weather could also have caused a build up of tropospheric haze and aerosol that enhanced the twilight.
Another and now more likely explanation is very high (15-25 km) and thin Type1 polar stratospheric clouds, PSCs. The exceptionally low temperatures needed to form them have existed for the last day or so. Type1 PSCs composed of nitric acid compounds are less colourful and bright than the better known Type2 or nacreous clouds made of ice crystals.
Image ©Adrian Smith, shown with permission.