Europe has so many grounded planes, which means skies less congested by contrails. Between that and the volcanic ash, sunsets have become extraordinary. 
Spaceweather hosts tons of pictures, and had the following on their website this morning:
Hard and sharp-edged volcanic dust is hazardous to aircraft, clogging engines that suck it in, and pitting windows that pilots need to see through. According to Eurocontrol, the intergovernmental body that manages European air travel, about 16,000 flights across Europe have been canceled. Stranded passengers have one consolation--sunrises and sunsets of rare beauty. Browse the links below for examples.
volcanic sky shots: from 
René of Schiphol, Amsterdam, Netherlands; from 
Manuel ten Hake of Zoetermeer, The Netherlands; from 
Vincent Phillips of Speke, Liverpool, England; from 
Toine Kuiper of Leende, Netherlands; from 
Jeffrey Berkhout of Nibbixwoud, Netherlands; from 
Katie-Anne Fitzgerald of Belton North Lincolnshire UK; from 
Alan C Tough of Elgin, Moray, Scotland.