"The inertial frame equations have to account for VΩ and this very large centripetal force explicitly, and yet our interest is almost always the small relative motion of the atmosphere and ocean, V' , since it is the relative
motion that transports heat and mass over the Earth. … To say it a little differently—it is the relative velocity that we measure when [we] observe from Earth’s surface, and it is the relative velocity that we seek for most any practical purposes." MIT essays by James F. Price, Woods Hole Oceanographic Institution (2006). See in particular §4.3, p. 34 in the Coriolis lecture