Mars' atmosphere is made mostly of carbon dioxide, with some nitrogen and argon. It has a very small amount of oxygen and carbon monoxide and tiny amounts of noble gases and other compounds. Earth's atmosphere is 100 times thicker than the atmosphere of Mars.Continue Reading
The atmosphere of Mars is so thin that liquid water probably can't persist there. Water ice sublimates directly into water vapor. Because of this, some scientists claim that Mars probably can't support the sort of life that is abundant on Earth. The atmosphere is also thought to be too cold to support liquid water.
However, scientists have also detected traces of methane, a gas that is often produced by living things, though it can also be produced by volcanic and other activity.
Despite the thinness of the atmosphere, clouds have been seen in Martian skies. There is also enough wind to kick up dust storms. These storms are violent and can last for months at a time. The heat from the blowing dust keeps the lower atmosphere of Mars relatively warm. The annual mean temperature is about negative 82 degrees Fahrenheit, though temperatures can go as high as 68 degrees F. It has even been known to snow on Mars. The snow is consists of carbon dioxide.Learn more about Planets