Mars Climate, Now and In the Past
Are the Clouds Made of Water?
This graph, taken by Mars Global Surveyor, shows proof that the clouds of Mars are made of water. The sequence shows actual water clouds moving across the face of Mars.
It wasn't until the Mariner 9 mission that proof was obtained that some of the clouds were actually composed of water. Whether there is water in the clouds is important. The atmosphere of Mars is cold enough for the clouds to be made of carbon dioxide. The presence of clouds of carbon dioxide would have a very different effect on the surface of Mars than the presence of clouds of water.