Atmosphere of Mars slowly decreased to very low concentrations, with no layer detectable above 35 km. The reporting scientists think that the observed polar ozone layers are the result of the same atmospheric circulation pattern that creates a distinct oxygen emission identified in the polar night and also present in Earth's atmosphere. This circulation takes the form of a huge Hadley cell in which warmer air rises and travels toward the south pole before cooling and sinking at higher latitudes. Mars is on a quite elliptical orbit and has a large axial tilt, which causes extreme seasonal variations in temperature amongst the northern
Atmosphere of Venus environment. Microbes in the thick, cloudy atmosphere could be protected from solar radiation by the sulfur compounds in the air. The solar wind may provide a mechanism for the transfer of such microbiota from Venus to Earth. The Venusian atmosphere has been found to be sufficiently out of equilibrium as to require further investigation. Analysis of data from the Venera, Pioneer, and Magellan missions has found the chemicals hydrogen sulfide (HS) and sulfur dioxide (SO) together in the upper atmosphere, as well as carbonyl sulfide (OCS). The first two gases react with each other, implying that something must produce them.