Image: skepticsociety.co.uk
The Story
Arsia Mons creates the cold, supersaturated pocket; the dust-free ice mechanism fits the cloud, but observations must still test it.
Air flowing over Arsia Mons rises, cools, and creates a narrow, exceptionally supersaturated region. In the new model, water vapor freezes directly into ice there, while winds carry the crystals westward into the long cloud. The result fits the cloud’s timing and shape better than conventional models, but several measurements still differ and direct confirmation is absent.
- What changedAdding homogeneous nucleation allowed models to reproduce the cloud’s defining elongated form and daily cycle.
- What remains openThe explanation is theoretical and simulation-based, with observational mismatches still requiring resolution.
- Researchers found that adding homogeneous nucleation to a Mars meteorological model reproduced the unusual characteristics of the Arsia Mons Elongated Cloud.
- The proposed mechanism requires rapid cooling near Arsia Mons, producing extreme supersaturation so vapor can form ice without dust.
- The simulations reproduce key features, but important mismatches remain and the mechanism needs observational confirmation.
Source mix
3 of 7 institutional
- 3 Journals & institutions
- 1 News reporting
- 3 Other / unclassified
Deeper Insight
The Arsia Mons cloud may make its own ice seeds. Mars is reminding us that Earth’s rules are often just local habits.
In Viking 2 images from 1976, a water-ice cloud stretched hundreds of miles from Mars’ Arsia Mons volcano. New modeling says extreme cold may let vapor freeze without airborne dust, then winds pull the ice into a ribbon. The fit is strong but incomplete. Mars keeps forcing open the rulebook we thought clouds followed.
- What it could changeMars climate models could account for ice forming directly from vapor in thin atmospheres.
- How it touches todayThe cloud shows how one stubborn observation can expose assumptions built from Earth’s weather.
- Our futurePlanetary science could keep finding worlds whose weather runs on rules we have not imagined.
- The Nature Geoscience model shows that homogeneous nucleation successfully reproduces the AMEC’s distinctive characteristics and strongly suggests direct ice formation from vapor on Mars.
- Earlier analysis treated the required supersaturation, around 10⁵, as implausible, but a cold pocket near Arsia Mons reaches conditions conducive to homogeneous nucleation.
- The process was considered unlikely in any natural atmosphere because it requires humidity far beyond ordinary condensation conditions.
Sources · 7
- 3 Journals & institutions
- 1 News reporting
- 3 Other / unclassified
What do these mean?
- Journals & institutions. Published in a peer-reviewed journal, or from a university, government body, court or other institution.
- News reporting. Journalism: newspapers, magazines and news sites.
- Other / unclassified. A site we have not classified yet. This says nothing good or bad about it.
Featured · Primary source · nature.com
Homogeneous ice nucleation from water vapour suggested by elongated clouds on Mars | Nature Geoscience
Journal · peer-reviewed
Homogeneous ice nucleation from water vapour suggested by elongated clouds on Mars | Nature Geoscience - Article - Published: 07 October 2026 # Homogeneous ice nucleation from water vapour suggested by elongated clouds on Mars - J. Hernández-Bernal ORCID: orcid.org/0000-0001-6980-155X 1, - A. Määttä
Read sourceAnalysis · doi.org
Homogeneous nucleation on Mars. An unexpected process that deciphers mysterious elongated clouds
Journal · peer-reviewed
# Homogeneous nucleation on Mars. An unexpected process that deciphers mysterious elongated clouds Published: 2025-07-09. 0 citations. ## Abstract Homogeneous nucleation has not been considered a possibility in cloud formation processes in the atmosphere of Mars (e.g. Clancy et al., 2017), since Mää
Read sourceAnalysis · sciences.sorbonne-universite.fr
A new cloud particle formation process revealed by an extraordinary cloud on planet Mars | Sorbonne Université| Sciences & Ingénierie
Other
A new cloud particle formation process revealed by an extraordinary cloud on planet Mars | Sorbonne Université| Sciences & Ingénierie # A new cloud particle formation process revealed by an extraordinary cloud on planet Mars On some mornings, a spectacular ice cloud nearly 2,000 km long forms downwi
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