Clouds and aerosols are important components of the climate system, impact remote sensing, affect human health, and are tightly coupled to radiation, chemistry and dynamics. This class covers the basic concepts in cloud and aerosol physics and chemistry in the context of the leading problems in climate, Earth history, air pollution, and weather. Examples include: dust storms; volcanic eruptions and climate; the extinction of the dinosaurs; nuclear winter; clouds and climate; thunderstorms, and lightning. Recommended restriction: junior and senior level students.