Scientists Model Mars' 1,000-Mile Arsia Mons Cloud Using 'Exotic Physics'

A thin, extremely long cloud that emerges each Martian spring and summer near the volcano Arsia Mons has finally been modeled, with results pointing to a physical process never directly observed in any planet's atmosphere. First recorded by a probe in 2018, the Arsia Mons Elongated Cloud (AMEC) stretches over 1,000 miles—roughly the distance from New York to Kansas City—before dissipating, a cycle that repeats for several months. Jorge Hernández-Bernal, a planetary scientist at Paris' Sorbonne Université and lead author of the study published in Nature Geoscience, said the team needed to incorporate 'exotic physics' that is in textbooks but treated as theoretical and usually thought not to occur in nature. The work suggests AMEC forms through homogeneous nucleation, in which vapor turns directly into ice crystals without particles such as dust or salt, which Hernández-Bernal likened to condensation appearing in the middle of a room rather than on a window. The process demands a 30-degree Celsius temperature drop within 10 minutes and high relative humidity; wind hitting the 65,000-foot-tall volcano generates a wave that lifts moist air rapidly. Humidity levels required exceed any measured on Earth by more than 100,000 times, and such levels on Mars were previously unknown. The story originally appeared on WIRED Czech Republic and Slovakia, translated from Czech.