The atmospheric temperature structure of Titan.

The thermal structure of Titan's atmosphere is determined by competing factors; the organic haze absorbs solar energy high in the atmosphere allowing only 10% to reach the surface while collision induced opacity in the thick troposphere produces a strong greenhouse effect warming the surface temperature by 21K. The antigreenhouse effect of the haze cools the surface by 9K and the net effect is that the surface temperature (94K) is about 12K warmer than the effective temperature. Early in Titan's history, 3 - 4 Gyr ago, its surface was probably cooler by about 20K primarily due to the reduced solar luminosity. To refine the models of Titan's past and present climate one needs a more complete understanding of the processes that set the H₂ mixing ratio and determine the haze formation rate.