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Evaporation from soil

Evaporation occurs when water changes from its liquid form into vapor. Energy is required for the change to take place because water molecules need to break their bonds in order for the water to turn into a gaseous state. This energy is normally acquired from heat (eg. from the sun on a hot sunny day)or as kinetic energy from the wind. The evaporation process is an important part of the water cycle.

Evapo-transpiration is the combination of water evaporation from the soil and transpiration in plants. These processes lead to significant loss of moisture from the soil. If the rate of evapo-transpiration taking place is higher than the rate of precipitation or rainfall, then the land will become dry and arid.

Water is lost from the soil surface through evaporation. The heat from the sun provides energy required by the water molecules to break their bonds, turn into water vapor and evaporate from the soil surface. As the number of water molecules in the soil reduces, capillary action will help pull more water molecules from further within the soil towards the surface, enabling further evaporation.