ABSTRACT
Evaporation results from complex energy and mass exchanges and can occur on any humid surfaces in contact with air. The change of liquid water to vapor consumes energy (latent heat of vaporization 2.46 106 J kg1). The water vapor diffuses in the air and is taken away by air convection. This process cools the surface heated by radiation (net radiation) or eventually by convection mostly during the day. Then evaporation increases with surface availability of water and energy. The reverse of this process is called condensation (water and energy gain). Unit used for evaporation flux density (or condensation) is mass of water by unit of surface and unit of time (mass flux: kg1m2 sec1 or mm day1; or energy flux Wm2).
