Atmosphere of Mars and southern hemispheres. Mars's temperature difference greatly influences the amount of water vapor in the atmosphere, because warmer air can contain more moisture. This, in turn, affects the production of ozone-destroying hydrogen radicals. In early 2016, Stratospheric Observatory for Infrared Astronomy (SOFIA) detected atomic oxygen in the atmosphere of Mars. This was the first time in forty years it was detected, the last time being the Viking and Mariner missions in the 1970s. Molecular nitrogen (N) is present in the atmosphere at 1.9%. Measurements by various robotic missions, and analyses of Martian meteorites, show that the atmosphere is enriched in
Ozone often considered the higher elevations beneficial because of their ozone content. "There is quite a different atmosphere [at higher elevation] with enough ozone to sustain the necessary energy [to work]", wrote naturalist Henry Henshaw, working in Hawaii. Seaside air was considered to be healthy because of its believed ozone content; but the smell giving rise to this belief is in fact that of halogenated seaweed metabolites. Much of ozone's appeal seems to have resulted from its "fresh" smell, which evoked associations with purifying properties. Scientists, however, noted its harmful effects. In 1873 James Dewar and John Gray McKendrick documented that