We study the climate dynamics of Titan by developing a hierarchy of planetary climate models and theories. We begin with a one-dimensional radiative-convective model of Titan's atmosphere including the greenhouse and antigreenhouse effects and a generalized moist convection scheme. Our simulations indicate the thermodynamics of methane evaporation and condensation play fundamental roles in establishing deep, precipitating convection while maintaining surface energy balance with the weak solar forcing at Titan's surface.

We then derive an extension to a steady, analytic theory for the large-scale circulation of an atmosphere and apply the theory to Titan. The theory predicts Titan's meridional overturning circulation, or Hadley cell, spans the globe. Titan's Hadley cell tends to eliminate latitudinal temperature gradients, which is consistent with the observed weak equator-to-pole surface temperature gradients. We expect Titan's Hadley cell to globally converge moisture into the large-scale updraft and suppress convection everywhere else; resulting cloud patterns should appear sparse and isolated in latitude.

We then study the seasonal cycle in a zonally symmetric general circulation model of Titan's climate with an unlimited surface supply of methane. This model produces condensation consistent with the position and timing of observed clouds, but only with the thermodynamic effect of methane condensation and evaporation included. The large-scale circulation in our simulations latitudinally oscillates with season, which in the annual mean dries the low-latitude surface. However, self-consistent drying of the surface requires an accounting of the methane reservoir.

Finally, we present zonally symmetric general circulation model simulations with a soil model for the lower boundary and a finite reservoir of methane. Due to annual-mean moisture divergence of the oscillating large-scale circulation, more than 50 m of liquid methane is removed from the low-latitude surface and deposited at mid and high latitudes. Simulations with total reservoir depths below 50 m completely dry the low latitude surface. All simulations with the soil model produce condensation at positions and times consistent with observed clouds.