mesopause In the atmosphere, the inversion at about 80 km height, which separates the mesosphere from the thermosphere above. The first 10 km of the mesopause are almost isothermal. The mesopause is liable to be marked by noctilucent cloud composed of ice crystals on meteoric dust. See also ATMOSPHERIC STRUCTURE.

mesopause In the atmosphere, the inversion at about 80 km height, which separates the mesosphere from the thermosphere above. The first 10 km of the mesopause are almost isothermal. The mesopause is liable to be marked by noctilucent cloud composed of ice crystals on meteoric dust.