Atmospheric waveguide

The parameters of atmospheric waves such as group velocity or vertical wavenumber depend on mean flow direction and strength. Thus, for instance westerlies might be a good waveguide for eastward-traveling waves, but might strongly dissipate westward-traveling waves because the vertical wavenumber decreases or increases, respectively. Modification of the waves' group velocity will chage their speed of meridional propagation, directing them more polewards or more equatorwards.