The Rossby number (Ro) is a dimensionless number consisting of the ratio of inertial (e.g., centrifugal) force to Coriolis force. It is used in modeling atmosphere and ocean dynamics. It is defined as:
Ro = U / Lf
The convective Rossby number, of interest in the study of convection in stars and planets and the resulting dynamos, is the ratio of a buoyancy force to the Coriolis force.