This combination of text and reference book describes the physical, plasma and chemical processes controlling the behaviour of ionospheres, upper atmospheres and exospheres. It summarises the structure, chemistry, dynamics and energetics of the terrestrial ionosphere and other solar system bodies, and discusses the processes, mechanisms and transport equations for solving fundamental research problems. This second edition incorporates new results, model developments and interpretations from the last ten years. It includes the latest material on neutral atmospheres; the terrestrial ionosphere at low, middle and high latitudes; and planetary atmospheres and ionospheres, where results from recent space missions have yielded fresh data. Appendices outline physical constants, mathematical formulas, transport coefficients, and other important parameters for ionospheric calculations. This is an essential resource for researchers studying ionospheres, upper atmospheres, aeronomy and plasma physics. It is also an ideal textbook for graduate-level courses, with supplementary problem sets, and solutions for instructors at www.cambridge.org/9780521877060.