Structure of polar mesospheric clouds seen from a geostationary satellite Original Research Article

Examination of a large number of images of polar mesospheric clouds has shown structure and height changes are present quite frequently. The thickening of the cloud layer, the splitting of a cloud layer, the changing height of a cloud layer are all ascribed to the presence of waves with rather long wavelengths in the cloud layer. They may well be planetary waves rather than the more localised waves seen commonly in noctilucent clouds.