Terrestrial radiation emitted by the Earth's atmosphere (long wave) is a key component of the energy balance at the Earth's surface. An important research question is how this terrestrial radiation is coupled to the evaporation of water at the surface. In this work, we evaluate a new laboratory wind tunnel system designed to measure the evaporation rate of a water surface exposed to different levels of terrestrial radiation.

Here we test a maximum evaporation theory that acknowledges the interdependence between radiation, surface temperature, and evaporation over saturated land. We show that the maximum evaporation approach recovers observed evaporation and surface temperature under non-water-limited conditions across a broad range of bio-climates. The implication is that the maximum evaporation concept can be used to predict potential evaporation that has long been a major difficulty for the hydrological community.