Take a glass of water [1]... concepts from physical chemistry used in describing the behaviour of aerosol and cloud droplets

Abstract

This is the text of a lesson explaining the concepts of kinetic gas theory, diffusion theory and thermodynamics used in describing the formation and growth of aerosol and cloud droplets in the atmosphere. The classical Koehler theory and its extensions are derived in a step-wise approach, starting from clean laboratory systems and ending with the polluted atmosphere. The meaning of the Koehler theory is analysed. Some comments follow regarding the central role the theory still plays in atmospheric research today; it indeed forms a formal framework to link air pollution and climate change.