Scientists Explain How Mars's Arsia Mons Cloud Forms Without Dust

A model based on ESA's Mars Express data suggests the Arsia Mons Elongated Cloud may form via homogeneous ice nucleation from water vapor, with no dust particles involved. Such a process has never been observed in any planetary atmosphere before.

• The cloud stretches up to 1,800 km and evaporates within hours each morning
• In simulations air rises kilometers in minutes, cooling 30°C in 10 minutes
• Homogeneous nucleation needs humidity 100,000 times higher than on Earth
• Data came from Mars Express cameras VMC, HRSC and OMEGA