The TES instrument has identified water-ice clouds using the infrared
spectral signature of ice. These clouds are warmer than the surface at night
and cooler during the day. This set of four images shows the occurence of
clouds over the Tharsis volcanic region, which includes Olympus Mons and three
other large volcanoes. This area is the cloudiest region that TES has observed.
In addition, the TES has discovered that clouds cover this region at night,
in addition to those that are often observed in visible images. The variations
in water-ice cloud occurrence will provide important clues to the temperature
and dynamics of the Martian atmosphere, as well as clues to the transport of water
between the surface, atmosphere, and poles.
The four images below were acquired on four separate orbits (17, 24, 31,
and 22, from left to right) as the MGS spacecraft approached the planet. Clouds
over the Tharsis region are clearly evident as the planet rotates.
