Evapotranspiration: A Component of the Water Cycle

Abstract

Evapotranspiration as a process is part of the water cycle of the Earth; it is the most important consumer of energy, creating the link between water and energy cycles of the Earth. The physics of water phase change is briefly presented. Consumption of energy to change liquid water into water vapor cools the biosphere, thus allowing the creation of suitable conditions for life on the Earth. This chapter contains basic information about the Earth and continents’ water cycle and its components, as well as the energy balance structure of the Earth. The kinetic theory of fluids is used to quantify the evaporation process because it depends on the properties of an environment, allowing us to find the most important properties of the environment influencing evapotranspiration. The kinetic theory of evaporation can help us understand evaporation as a process, but does not allow use in directly quantifying it; therefore other methods should be used.