Tropical convective clouds distribute water vapour across the tropical tropopause layer (TTL), which affects the radiative budget in both the troposphere below and the stratosphere above. Water isotopes can be used as tracers to conclude on the history of water vapour in these altitudes, i.e. whether it went through phase change processes and was part of ice or liquid clouds before. de Vries and coworkers used an innovative modelling scheme capable of simulating convection together with the phase-change processes producing the isotopic signatures to simulate tropical ice clouds and compare their simulations to respective observations. By this, they were able to disentangle processes of convective updraft versus cirrus cloud formation in tropical cloud systems and demonstrate how the isotopic fractionation of water vapour does help to distinguish respective processes. Over all, this paper is innovative and a considerable step forward in studies of convection and transport of water vapour into the upper tropospher/lower startosphere (UTLS).