An oscillation in the motion of particles of a fluid, often with a greater or lesser degree of periodicity, and which may remain stationary or propagate downstream. In the atmosphere, waves may involve vertical or horizontal motion, or both. Waves may arise from a flow across a physical obstacle (such as airflow across a mountain range), or from instabilities along the boundary between fluids of differing density or temperature (as in the formation of a wave cyclone on a quasi-stationary front). See gravity wave; lee wave; Kelvin wave; Kelvin–Helmholtz instability; planetary wave; Rossby wave.
Subjects: Meteorology and Climatology.