ABSTRACT
The hydrologic cycle starts when solar energy changes water from the liquid or solid state to the gaseous state. The hydrogen bonds provide the force holding the molecules together as a coherent liquid mass which we know as water. This chapter first identifies the meteorological factors that control evaporation, and then discusses several methods for measuring and estimating evaporation. It examines the meteorological variables that control evaporation from shallow lakes. Evaporation from shallow lakes follows meteorological conditions more closely than evaporation rates from deep lakes because of energy storage in deep lakes. Here the author uses energy-balance equations to analyze energy input, output and storage. Evaporation equations use combinations of the three meteorological factors solar energy, vapor pressure deficit and wind speed. This chapter discusses two basic approaches the mass transfer/aerodynamic approach, which uses vapor pressure deficit and wind speed, and the so-called 'combination method' which combines solar energy with the mass transfer/aerodynamic method.
