Chemistry and composition of planetary atmospheres

Keywords: Chimie de l’atmosphère, photochimie, cycles biogéochimiques, climat
Prerequisites: Bases en thermochimie, cinétique chimique, transfert de rayonnement, mécanique des fluides, mais des rappels seront faits en cours

A planetary atmosphere is a chemical reactor driven in the same time by chemical, dynamical, thermodynamical and radiative processes. On Earth, the reactive minor constituents of the atmosphere play an important role in filtering UV radiation (ozone), climate (methane, ozone, particles) or atmospheric pollution (ozone, oxides of nitrogen, particles). These minor constituents are emitted at the planet surface in reduced form or produced in the atmosphere, and are generally oxidized during low-temperature catalysed photochemical reactions before being deposited on the ground. The study of the stratospheric ozone layer makes it possible to understand the coupling between chemical reactivity, transport and radiation, and to draw general laws in atmospheric chemistry. It then becomes possible to account for more complex environments, such as the urban boundary layer, and for the atmospheric part of biochemical cycles. These general laws are finally applied to the study of the planetary atmospheres of our solar system to account for the variability of their composition, in time and space.