Terrestrial Planets, Page 14: [Previous Page] [Next Page] [Class Home Page] Textbook pages 181 - 201

The Ice Caps on Mars: Both CO₂ and Water!



Carbon Dioxide (CO₂), is the main constituent of the Martian atmosphere. At these low pressures, it only exists as a gas or solid (this is true on Earth, too. It's called DRY ICE!).

The CO₂ moves from the atmosphere to solid frost on the ground, depending on the seasons. During the long winter, the CO₂ will condense out of the atmosphere, particularly over the polar caps. This ice will form down to latitudes of 40^o (Cincinnati Latitudes). During the Spring, the CO₂ ices sublimate directly back into the atmosphere.







During the Northern Summer, all the CO₂ ices sublimate, leaving behind water ices and dust. The CO₂covering the Southern Polar Cap never entirely disappears, so it is not known if water ice lies below it. Click HERE for animated gif of the above figure, and Here for a short movie.