Arctic’s 40-year record low temperatures spawn rare clouds

NASA’s MERRA-2 climate model reveals that the Arctic stratosphere has reached a 40-year record low for December, creating a sudden appearance of polar stratospheric clouds (PSCs) far beyond their usual Arctic confines.

Recent observations have revealed a remarkable surge in polar stratospheric clouds (PSCs), often referred to as the most beautiful clouds on Earth due to their aurora-like colors.

This sudden increase is attributed to a 40-year record low in temperatures within the Arctic stratosphere for the month of December, as indicated by NASA’s MERRA-2 climate model.

PSCs form under extremely cold conditions, typically around -85 °C (-121 °F), in the otherwise cloudless stratosphere. The unusual cold snap has caused these clouds, usually confined to the Arctic, to descend all the way to mid-latitudes.

Notable sightings have been reported over Locarno, Switzerland, Torun, Italy, and Lausanne, Switzerland, locations well beyond the normal range of PSCs.

This phenomenon represents a significant deviation from the typical January start of the PSC season. The current extreme cold wave has not only given rise to an early onset of these clouds but also suggests the potential for increased occurrences in the coming weeks.

On December 24, 2023, the Arctic stratosphere is warming but it’s still cold enough for polar stratospheric clouds.

References:

¹ Record-cold weather in the stratosphere – SpaceWeather – December 23, 2023

Featured image credit: Branca Cristina via SpaceWeather. Captured on December 22, 2023, at Locarno, Switzerland