That is the name first given to it by Joanne Malkus in the 1950's. I have only recently appreciated the sigificance of the phenomena for the modelling of air pollution mechanisms. Joanne's studies were made by Catalina flying boat from Porto Rico when she was based at Woods Hole Oceanagraphic Institution, to which I made a visit in 1953. I have many slides, including one series which shows the penetration of this inversion by a thermal from a forest fire which was exceptionallly hot, viewed from Boulder, Colorado in 1975 or thereabouts. This inversion confines urban air pollution most effectively, and my talk will explain the relevance of the Trade Wind cumulus to this