Energy Fluxes at the Earth’s Surface

Evaporation and sensible heat flux into the atmosphere require the availability of some form of energy at the earth-atmosphere interface. This question can be treated quantitatively by considering the equation for the energy budget for a layer of surface material. Depending on the nature of the surface, this layer may consist of water, or of some other substrate like soil, canopy or snow; although this layer can be taken to be infinitesimally thin, it may sometimes even comprise a lake or a vegetational canopy over its entire depth.