Methane is near its triple point at Titan's surface. On the frigid moon of Saturn, this hydrocarbon is a fluid analog of water on Earth. Transitions among the phases of methane give rise to a meteorological cycle that can intimately link the atmosphere and surface. Despite the evidence for solid and liquid methane in Titan's atmosphere, spectroscopic retrievals of aerosol haze opacities, cloud properties, and surface reflectivities have not included opacity due to condensed-phase methane. By increasing the sophistication of models used to interpret observations, new atmospheric phenomena are being measured on Titan. The observations are revealing a world with an atmosphere that has a strikingly similar level of complexity to our own. I will summarize and review the fundamental properties of Titan's atmosphere, describing familiar atmospheric physics in an exotic new context.

Note: This is the second part of a double-header on the atmosphere of Titan. The first part, which is being hosted by Astronomy (Physics and Astonomy Building, A102, 4PM Thursday 15th May):

Condensed-phase methane and tropospheric meteorology on Titan (Part I)

The largest moon of Saturn is enshrouded by aerosol hazes, making the lower atmosphere and solid surface difficult to study. Recent advances in IR instrumentation, adaptive optics, and the Cassini/Huygens mission have produced numerous, sometimes difficult to reconcile, views of this environment. I will describe how a significant discrepancy between near infrared observations and radiative transfer models can be resolved by a rudimentary treatment of large methane droplets or solid methane particles in Titan's atmosphere. I will present measurements from ground-based VLT/SINFONI and Keck/OSIRIS instruments, as well as the Cassini/VIMS spacecraft, while explaining a technique for enhancing contrast in haze-obscured and surface-contaminated images of the lower atmosphere. Views of changing global-scale hazes, cloud evolution, and indications of precipitation will be discussed in the context of past predictions that have been confirmed (or refuted) by new observations.

-- TWikiGuest - 29 Feb 2008