In a recent paper Rossby has discussed the effect of the latitudinal variation of the Coriolis force on the propagation of oceanic and atmospheric disturbances (2). He showed that the velocity c of a disturbance in an incompressible atmosphere on a plane earth when only the effect of the latitudinal variation of the Coriolis force is considered is given with sufficient accuracy by the formula...
Haurwitz, B.. 1940. "The motion of atmospheric disturbances." Journal of Marine Research 3, (1). https://elischolar.library.yale.edu/journal_of_marine_research/560