Professor Herbert Huppert, DAMTP, University of CambridgeCambridge Fluids Network - fluids-related seminars25 November 2016 1:00pmLR11, Cambridge University Engineering DepartmentI would present a brief description of a volcanic eruption, the formation of a volcanic plume and its intrusion at the height of neutral density into the stratified atmosphere; the intrusion rate determined by balance of forces, by balance of terms in the governing equations and by a similarity form of solution, all of which agree, but are, unfortunately, incorrect ! I will go on to develop the correct, quite different, solution and account for the extra effects of drag and wind. I will end with a observational graph, which I like, but some others don't, collapsing the data for spread as a function of down-stream distance, an aspect I am still working on.