7 – Atmospheric Dynamics

Publisher Summary This chapter introduces a framework for describing and interpreting the structure and evolution of large-scale atmospheric motions. It considers motions with horizontal scales of hundreds of kilometers or longer, vertical scales on the order of the depth of the troposphere, and timescales on the order of a day or longer. Motions on these scales are directly and strongly influenced by the Earth's rotation, they are in hydrostatic balance, and the vertical component of the three-dimensional velocity vector is more than three orders of smaller magnitude than the horizontal component but is nonetheless of critical importance. The chapter also introduces some concepts and definitions that are useful in characterizing horizontal flow patterns. It is followed by a more extensive review on the dynamics of large-scale horizontal motions on a rotating planet. The chapter further introduces the system of primitive equations, which is widely used for predicting how large-scale motions evolve with time. The chapter concludes with brief discussions on the atmospheric general circulation and numerical weather prediction.