Physical properties of water

Abstract

Water covers more than two third of Earth’s surface and thus is the most prevalent substance on Earth. It is also the only liquid on Earth occurring simultaneously in all three phases: ice, liquid water and water vapour. Its dynamics are linked to the great expenditure of energy to keep in motion ‘the water cycle and thus stabilize Earth’s climatic conditions. Water’s occurrence and its movement are preconditions for biomass production. In this chapter, the physical properties of water are quantitatively described to enable a calculation of its transport in the hydrosphere. Moreover, the molecular structure of water that determines water’s physical and transport properties is treated. Soil water is characterized as a solution of solute low concentration, and the solubility of gas in water is defined and quantified. Water density, compressibility and expansion, as well as water’s surface tension and viscosity are defined, and their dependence on temperature is explained.