The composition of the atmosphere
are very different (the Earth is predominantly nitrogen
while Mars is predominantly carbon dioxide
). They do have similar global circulation patterns. Because the Earth has large oceans
to buffer the surface temperature
, and because carbon dioxide has a higher thermal emission
, the temperature of the martian atomosphere is more sensitive to fluctuations in solar
energy as a result of the days and seasons with the temperature varying from -125 to 15o
C. Mars also faces the sun obliquely with respect to its rotation, resulting in more surface heating in the tropics than at the poles. The Coriolis
effect, caused by planetary rotation, does deflect north-south moving air masses as it does on Earth, creating east-west wind currents. These atmospheric cycles are correlated with other geophysical cycles of carbon dioxide, water and dust.
The seasonal polar ice caps on mars are made of carbon dioxide, caused in the winter by the freezing of approximately one quarter of the atmospheric content of carbon dioxide! The permanent polar ice caps are made of water, which is where nearly all the water on Mars is found. The water laden ice caps are actually much larger than they appear to visual inspection because of the large layers of dust covering much of the extended edges of the caps. Because of the atmospheric conditions on Mars, water is currently either stable as a solid, or as vapor. Liquid water is practically nonexistant.
The Martian dust itself cycles seasonally as the wind picks up and drops off. Global dust storms occur during the southern summer and spring months, because that is when the heating of the atmosphere and its resulting circulation are
the most intense. The dust is also believed to be responsible for nucleating ice crystals in the polar ice caps and in large ice vapor clouds.
The understanding of the water cycle on Mars is of great interest to NASA, in order to determine if making liquid water available is in fact practical.