Maximum upper atmospheric turbulence results in the mesosphere from convective and/or dynamic instabilities induced by gravity waves. For the first time, by comparing the vertical accelerations induced by wind shear and the buoyancy force, it is shown that the critical Richardson number can be estimated. This new approach, for the first time, makes it is possible to establish and estimate the temperature gradient impact on dynamic instability development.

For the first time, the authors show that, by using the similarity theory, the same formula can be obtained for the eddy diffusion coefficient as the commonly used formula derived by J. Weinstock. Our results also explain the discrepancy between the large cooling rates calculated by the authors and the temperatures given by the MSIS-E-90 model.