At https://spaceweather.com/ (5th December 2019) we have details of a planetary wave supercharging noctilucent clouds in the southern hemisphere. NASAs AIM spacecraft detected the phenomena and took images (see below). Planetary waves are huge ripples of temperature and pressure that flow in the atmosphere in response to coriolis forces. In this instance the planetary wave is boosting noctilucent clouds over Antarctica, causing them to spin out to latitudes where they are not normally seen. In this instance, over New Zealand. The wave is actually concentrating a mass of cold water vapour in the mesophere and causing the mixture to pinwheel counter clockwise around the North Pole …
… and the same story is at https://tallbloke.wordpress.com/209/2/06/planetary-wave-supercharges-sou… …