This book examines the fundamental physical processes that control planetary climates, from convection and radiation to escape of atmospheres, evaporation, condensation, atmospheric chemistry, and the dynamics of rotating fluids. It looks at the climates of the planets in order of distance from the Sun, starting with Venus and ending with planets around other stars. The greenhouse effect and climate evolution are discussed, along with basic physical processes such as convection, radiation, Hadley cells, and the accompanying winds. It also considers the “faint young Sun paradox,” illustrated by Mars, and the effect of planetary rotation on climate, the influence of sunlight and rotation on weather patterns, and Neptune's extraordinary strong winds.