Researchers say they have finally reproduced a strange Martian cloud on a computer, and the recipe calls for a process no one has caught in any planet's atmosphere. The Arsia Mons Elongated Cloud (AMEC) stretches roughly 1,000 miles (1,610 km), and it has baffled scientists since a probe first recorded it in 2018.
The work appears in Nature Geoscience, and Ars Technica covered it in October 2026. We haven't been able to confirm the date the paper itself was published, and the quotes here come from Ars Technica's reporting, not from our own interviews. Lead author Jorge Hernández-Bernal of Sorbonne Université in Paris said the simulated cloud only showed up once the team added what he called "exotic physics," meaning something found in textbooks but usually assumed not to occur in nature.
Ice forming without dust
Earth's clouds usually start when water vapor condenses on specks of dust or salt. The Mars model instead relies on homogeneous nucleation, in which vapor becomes ice crystals with nothing to cling to. Hernández-Bernal likened it to moisture appearing in the middle of a room instead of on the window.
The conditions are demanding. According to the researchers, the air has to drop by 30° Celsius inside 10 minutes while holding very high relative humidity.
How the volcano sets it off
The trigger, the study says, is Arsia Mons itself, a volcano roughly 65,000 feet tall. Wind striking the mountain builds a strong wave that hurls moist air high up within minutes.
As Ars Technica reports it, the humidity needed is more than 100,000 times what has been measured on Earth. The report doesn't say which Earth measurement serves as the baseline, such as the upper atmosphere or sea level, so treat that figure with care until the paper's own comparison is checked. Hernández-Bernal pointed out that we understand Martian air much less well than our own, so matching the cloud is, as he put it, a big success.
What is still unproven
This is a simulation, not an observation. Our source doesn't say how the humidity figures might be checked or whether any spacecraft is planned to look. The same process has long been considered possible high in the skies of Venus and Earth, yet it has never been seen.
Watch for other teams to test the model against orbital data. Would you accept a model that matches a cloud as proof, or do you want a spacecraft to catch it in the act?
Sources
- 1.A 1,000-mile cloud on Mars may reveal physics never seen in nature · Ars Technica
Reported by the WattsUpNext desk from the sources linked below. Spot an error? Tell us at corrections@wattsupnext.com.
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