Composition of Martian Atmosphere
The atmosphere of Mars with a mean molar mass of 43.34 g/mol is mainly composed of carbon dioxide (CO2). It has an average atmospheric pressure of 600 Pa (pascals) on the Martian surface which is very low in comparison to the Earth’s mean sea level pressure of 101.3 kPa. The Martian atmosphere being quite dusty gives the sky of its planet a light brown or orange-red color when viewed from the surface.
It may also be interesting to know that there exists a significant annual variation in the atmospheric composition and pressure around the Martian poles. Each Martian pole in its winter experiences continual darkness which makes it so cold that a considerable portion (as much as 25%) of the atmospheric carbon dioxide solidifies at the polar surface. In the summer, exposure to the sunlight and the resultant heating cause solid carbon dioxide to sublime back into the atmosphere. These changes result in variation of CO2 amount in the atmosphere changing the atmospheric pressure and composition besides providing the way to creation of water-ice clouds.