(15.8.2018) Harvey and her colleagues are still working to understand how the extra water got up there. One possibility involves planetary wave activity in the southern hemisphere which can, ironically, boost the upwelling of water vapor tens of thousands of miles away in the north. The phenomenon could also be linked to solar minimum, now underway. It is notable that the coldest and wettest years in the mesosphere prior to 2018 were 2008-2009–the previous minimum of the 11-year solar cycle.