Abstract: Since the contradiction between the nondivergent assumption of Rossby waves theory and the concept of physics fluctuation, this paper discusses that the mutual conversion between implicated vorticity and relative vorticity is practically required by divergence. From the view of the geostrophic adaptation theory, the nondivergent assumption of Rossby is actually assumed that the process of the geostrophic adaptation is infinitely fast, which does not contradict the concept of physics fluctuation. Finally, the distribution characteristics of divergence in long wave and its physical correlation with long wave velocity are analyzed based on the difference between streamline and trajectory.