Aerosols in Titan's Atmosphere

Aerosols in Titan's atmosphere play important roles in the transfer of solar and thermal radiation, in Titan's heat balance, in forcing atmospheric dynamics, and as a sink for photochemical reactions. In this chapter we briefly summarize the history of our knowledge of their distribution and optical properties before concentrating in greater detail on current knowledge of their properties and roles in the physics and chemistry in Titan's atmosphere. We discuss the size, shape, optical properties, and the vertical distribution of Titan's aerosols. We discuss variations of the optical properties of the aerosols with wavelength, variations of the distribution of the aerosols over the disk of Titan, and the seasonal and long-term variations in structure. We discuss the visible and thermal opacity of the aerosols, and their roles in Titan's heat balance. We summarize the history and current state of laboratory simulations of these particles, and present our understanding of their formation and life cycles in one and two-dimensional microphysical models. We also discuss the presence, location, and variations in condensation clouds over Titan's disk. Finally, we indicate the prospects for further progress in understanding the origin, distribution, and properties of Titan's aerosols in the future.