Methane rain on Titan

摘要: Abstract We use a new set of absorption coefficients for methane, hydrogen, and nitrogen, as well refractive indices haze methane clouds, in multiple scattering radiative transfer model to reexamine the Voyager IRIS infrared spectra Titan. find, agreement with previous studies, that hydrogen composes 0.2 0.6% atmosphere. also find relative humidity at surface may be excess 60%, clouds probably exist from altitudes below 10 km up about 30 km, cloud particle radius is larger than 50 μm so particles should classified rain, optical depth are present typically order 2 5 both visible. infer patchy. The have only small effect on spectrum Titan, not very significant visible radiation either. large sizes low depths Titan Earth can understood if Titan's high altitude major source condensation nuclei. Then growth limited by supersaturation until raindrop reached. investigators, play an important role wavenumber region 500 600 cm−1. suggest latitudinal variations brightness temperature these wavenumbers due primarily observed layer, rather surface. presence argon required interpret spectra. Further measurements pressure-induced conditions appropriate needed, since data crucial our analysis.