Urgent! ! ! Wait online! Characteristics of upper atmosphere motion

The atmospheric region (about 60 kilometers) where the earth's atmosphere begins to ionize. The initial height of the upper atmosphere is not consistent. For example, some people regard sounding balls as the lower limit of the upper atmosphere, and some people call the atmospheric area above the top of the mesosphere (about 80 kilometers) the upper atmosphere. The layered structure of the upper atmosphere is not obvious. Atmospheric particles with high thermal velocity may escape from the earth's atmosphere, and gas particles in space may also enter the upper atmosphere.

Below 80 kilometers, the atmosphere is in a state of uniform mixing; However, above 80 km, the atmospheric turbulence gradually disappears, gradually transits to the molecular diffusion equilibrium state, and reaches the complete diffusion equilibrium above 120 km. Diffusion balance means that under the action of gravity field, the heavy components in the atmosphere are distributed in the lower layer and the light components are distributed in the upper layer, so that the average molar molecular weight of the atmosphere decreases with height. In the upper atmosphere, there are not only molecular movements, but also macroscopic movements such as global circulation, tides and acoustic gravity waves.