Climate of Titan

However the methane in the atmosphere causes a substantial greenhouse effect which keeps the surface of Titan at a much higher temperature than what would otherwise be the thermal equilibrium.

Recent computer simulations indicate that the huge dunes of soot like material raining down from the atmosphere in the equatorial regions may instead be shaped by rare storm winds that happen only every fifteen years when Titan is in equinox.

[12] Titan's lakes are largely placid, with few waves or ripples; however, Cassini has found evidence of increasing turbulence during the northern hemisphere summer, suggesting that surface winds may strengthen during certain times of the Titanian year.

[14] The findings of the Huygens probe indicate that Titan's atmosphere periodically rains liquid methane and other organic compounds onto the moon's surface.

[15] In October 2007, observers noted an increase in apparent opacity in the clouds above the equatorial Xanadu region, suggestive of "methane drizzle", though this was not direct evidence for rain.

[16] However, subsequent images of lakes in Titan's southern hemisphere taken over one year show that they are enlarged and filled by seasonal hydrocarbon rainfall.

[21] Calculations suggest that, as the northern hemisphere, where most of the lakes reside, enters the long Titanean summer, wind speeds might increase to 3 km/h, levels sufficient to produce waves.

[22] Waves have been observed on several occasions by Cassini RADAR and the Visual and Infrared Mapping Spectrometer since 2014, which were likely generated from summer winds[23][24] or tidal currents.

[28] This cell creates a global band of low pressure—what is in effect a variation of Earth's Intertropical Convergence Zone (ITCZ).

Unlike on Earth, however, where the oceans confine the ITCZ to the tropics, on Titan, the zone wanders from one pole to the other, taking methane rainclouds with it.

[30][31] Titan's clouds, probably composed of methane, ethane, or other simple organics, are scattered and variable, punctuating the overall haze.

One hypothesis is that it is currently raining (or, if cool enough, snowing) on the north pole; the downdrafts at high northern latitudes are strong enough to drive organic particles towards the surface.

One hypothesis asserts that the southern clouds are formed when heightened levels of sunlight during the Titanean summer generate uplift in the atmosphere, resulting in convection.