View of Olympus Mons from Viking 1

Pavonis Mons (MOC2-609)

Frost-covered Charitum Montes (MOC2-409)

The Martian mountain ranges...

Individual mountains do not affect the global weather so much as large mountain ranges that are hundreds to thousands of miles across. For instance, on Earth the Himalayan range has a very important effect on the Asian monsoon. On Mars, this large-scale topography is larger in vertical extent, and so plays a more important role in the Martian climate, affecting storms and other meteorological phenomena.

On Mars, as on Earth, individual mountains only tend to affect the climate in their immediate locality. During the day, air tends to move up the sides of large mountains (this phenomenon is akin to sea-breezes). As the air cools, water vapour can condense. Condensation of this nature on the flank of Mount Olympus has been observed by the Hubble Space Telescope.

As air moves over a mountain, it oscillates up and down on the mountain's leeward side. These waves are called lee waves or buoyancy waves. These waves have horizontal scales of a few miles across, and have been observed in Viking Orbiter images of Mars.