Nacreous or polar stratospheric clouds were spotted in the sky over Ireland this morning. They can form in winter high up in the stratosphere, 15 - 25 km high, at very low temperatures, below −78 °C (−108 °F). pic.twitter.com/zcSB1uB4GV

— Climate Services @ Met Éireann (@METclimate) December 21, 2023