1,000-Mile Martian Cloud Driven by Exotic Physics Never Seen Before

Researchers using data from the European Space Agency’s Mars Express orbiter have successfully modeled a mysterious 1,000-mile-long cloud that forms and vanishes on Mars every day, concluding that the phenomenon relies on theoretical physics never before observed in a planetary atmosphere. The feature, known as the Arsia Mons Elongated Cloud, emerges near a 12-mile-tall extinct volcano and stretches up to 1,100 miles long during the Martian spring and summer.

The wispy formation first caught the attention of scientists when a probe spotted it in 2018. Since then, the formation has appeared nearly every morning, growing gradually over several hours before evaporating completely as increased solar radiation triggers strong surface winds. Live Science noted that the cloud spans roughly one-twelfth of the Red Planet’s circumference, matching the distance from New York City to Miami.

Simulations Reveal Exotic Physics Above Arsia Mons

To crack the mystery, researchers published a study on October 7 in the journal Nature Geoscience utilizing Mars Express data to simulate the weather pattern. The team initially struggled to recreate the cloud using standard meteorological principles. Success came only after the researchers incorporated theoretical physical processes that are typically treated as textbook concepts rather than observable natural events.

Jorge Hernández-Bernal, a planetary scientist at Sorbonne Université, explained that the team found they needed to include “exotic physics … physics that, while included in textbooks, is treated as theoretical and usually thought not to happen in nature. It certainly hasn’t been seen in action before.” He added that once this physics was included in their simulations, the cloud emerged just as they had hoped.

On Earth, orographic clouds like the Levanter cloud over the Rock of Gibraltar form through heterogeneous nucleation. This process requires moist air to cool and condense into ice crystals around tiny airborne particles such as dust, salt, pollen, or soot. While Mars has plenty of atmospheric dust, the research team determined that the Martian cloud bypasses this middle step entirely.

Instead, the simulations point to homogeneous nucleation, where water vapor turns directly into ice crystals on its own without debris. Wired reported that Hernández-Bernal described the mechanism as akin to droplets of condensation appearing in the middle of a room rather than on a window. The process demands extreme atmospheric conditions, including relative humidity levels exceeding 100,000 times any value ever measured on Earth, alongside a sharp temperature drop of 30 degrees Celsius within 10 minutes.

Volcanic Waves Shape Daily Martian Weather

The towering geography of Arsia Mons plays a direct mechanical role in generating these extreme conditions. When local wind currents hit the slopes of the 65,000-foot-tall volcano, the obstacle triggers a powerful wave that launches moist air high into the atmosphere within minutes. Before this computer modeling, scientists did not know that such high humidity levels actually existed in the Martian atmosphere.