Earth ozone layer due to the subsequent conversion of atmospheric into. The ozone layer blocks ultraviolet solar radiation, permitting life on land. Other atmospheric functions important to life include transporting water vapor, providing useful gases, causing small meteors to burn up before they strike the surface, and moderating temperature. This last phenomenon is known as the greenhouse effect: trace molecules within the atmosphere serve to capture thermal energy emitted from the ground, thereby raising the average temperature. Water vapor, carbon dioxide, methane, nitrous oxide, and ozone are the primary greenhouse gases in the atmosphere. Without this heat-retention effect, the average surface
Life on Titan hydrogen concentration in the upper and lower atmosphere. Strobel found that the hydrogen concentration in the upper atmosphere is so much larger than near the surface that the physics of diffusion leads to hydrogen flowing downwards at a rate of roughly 10 molecules per second. Near the surface the downward-flowing hydrogen apparently disappears. Another paper released the same month showed very low levels of acetylene on Titan's surface. Chris McKay agreed with Strobel that presence of life, as suggested in McKay's 2005 article, is a possible explanation for the findings about hydrogen and acetylene, but also cautioned that other explanations