ABSTRACT
The evaporation of water from earth to atmosphere is primarily from the oceans, which occupy 71 per cent of the surface of the globe and account for 65 per cent of the evaporation into the atmosphere. In breaking from the mass the molecules do work which requires the utilization of the latent heat energy in the mass; thus evaporation leads to cooling of the mass. The main reason for an apparently limited interest in assessing evaporation probably relates to the much greater significance of evapotranspiration or potential evapotranspiration because of the relevance of a knowledge of these to agriculture. Just as energy was utilized for the evaporative process, so it must also be released for condensation, a most important source of energy in the atmosphere, of rising currents of heated air in clouds for instance. The cloud and rain associated with the Atlantic airmass appreciably lowers the temperatures but increases the vapour pressure and the relative humidity therefore soars.
