[astro-ph.EP] It is widely accepted that water vapor forms clouds by heterogeneous nucleation (condensation on pre-existing dry nuclei).
![Observation and modeling of the Arsia Mons Elongated Cloud (AMEC). (A) Observation by the Mars Express VMC imager41,42, at 8.5 a.m. Local Time. (B) Reference simulation assuming only heterogeneous nucleation, at 8.1 a.m. Local Time. (C) Same as B, but with homogeneous nucleation added. See also supplementary video S1.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/10/Homogeneous.png?resize=1200%2C720&ssl=1)
[astro-ph.EP] It is widely accepted that water vapor forms clouds by heterogeneous nucleation (condensation on pre-existing dry nuclei).