J. Geophys. Res. 118, 1945–1954 (2013).

The martian atmosphere has clouds composed of both water and carbon dioxide ice, but the processes by which these clouds form seem to be different to those on Earth. Cloud nucleation experiments suggest that, like on Earth, water ice nucleates on dust particles in the martian atmosphere, but with a temperature dependency not seen in analogous water ice clouds high in Earth's troposphere.

Daniel Cziczo at the Massachusetts Institute of Technology and colleagues used an experimental cloud chamber adapted to mimic martian environmental conditions to study the formation of clouds made solely of water ice. They found that, in a low-pressure and chemically inert atmosphere similar to that of Mars, water ice clouds can form due to nucleation around dust particles of a similar size to those found on Mars. However, the concentration of dust particles required for ice to nucleate is dependent on temperature, with higher concentrations of particles required for nucleation at lower temperatures.

This unusual temperature dependence could explain why previous cloud nucleation experiments have failed to simulate the observed cloud cover on Mars.