AOPP Seminar - H2O spectroscopy and Earth's radiative-convective boundary

The tropopause or radiative-convective boundary limits the vertical extent of convection and weather in planetary atmospheres, often with significant implications for the outgoing thermal radiation and remote observations. There is little consensus on theories for the tropopause, however (even on Earth), with many theories employing a `gray' approximation for thermal radiation. Here we consider recent ideas from terrestrial climate science which suggest to the contrary that H2O spectroscopy plays a leading role in determining the temperature and hence height of Earth's tropopause. We formulate these ideas in terms of a predictive theory based only on moist thermodynamics, radiative transfer physics, and the H2O absorption spectrum. We test the theory in Earth-like single column and GCM simulations, and briefly consider implications for other worlds.