A 1,000-mile-long water ice cloud appears daily over Mars’ Arsia Mons volcano, driven by exotic physics
never before observed in a planetary atmosphere.
Martian Cloud Formation Discovered
The European Space Agency’s Mars Express orbiter first spotted the cloud in 2018. It has reappeared nearly every morning during the Martian spring and summer since.
The cloud emerges as solar radiation triggers strong surface winds, grows for several hours, and then evaporates completely. A study published in Nature Geoscience by Jorge Hernández-Bernal and his colleagues at the LMD—founded by the French National Centre for Scientific Research (CNRS) and Sorbonne Université—successfully simulated the AMEC by incorporating theoretical physics previously thought to be absent in nature.
Physics of the Martian Atmosphere
On Earth, clouds typically form when water vapor creates droplets or ice crystals in the presence of tiny particles, such as dust or salt. The new research suggests the AMEC operates differently.
We found that we needed to include some 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. Once we included this physics in our simulations, the AMEC emerged just as we hoped.
Jorge Hernández-Bernal, lead author and planetary scientist at Sorbonne Université
The researchers noted that this process is wholly unexpected
and has never been directly observed in any planetary atmosphere.
Volcanic Influence on Atmospheric Patterns
The 12-mile-tall (20 km) extinct volcano Arsia Mons is central to the cloud’s formation. When wind currents strike the 65,000-foot-tall volcano, they generate a powerful wave that launches moist air into the upper atmosphere within minutes.
This rapid vertical movement triggers the necessary temperature and humidity spikes for the cloud to materialize. Before this modeling, it was not known that these specific humidity levels existed on Mars.
Hernández-Bernal noted that while scientists have assumed a similar phenomenon could occur in the upper atmospheres of other planets, including Venus and even Earth, it had never been observed until now. We don’t have nearly as much information about Mars’ atmosphere as we do about Earth’s, so reproducing the AMEC to this degree is a big success,
Hernández-Bernal said, adding, the result is remarkable.
Researchers have historically lacked detailed information regarding the Martian atmosphere compared to the extensive data available for Earth.
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