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Evaporation is an essential part of the water cycle. The sun (solar energy) drives evaporation of water from oceans, lakes, moisture in the soil, and other sources of water. In hydrology, evaporation and transpiration (which involves evaporation within plant stomata) are collectively termed evapotranspiration. Evaporation of water occurs when ...
Evaporation is a phase transition from the liquid phase to vapor (a state of substance below critical temperature) that occurs at temperatures below the boiling temperature at a given pressure. Evaporation occurs on the surface. Evaporation only occurs when the partial pressure of vapor of a substance is less than the equilibrium vapor pressure ...
The processes that drive these movements are evaporation, transpiration, condensation, precipitation, sublimation, infiltration, surface runoff, and subsurface flow. In doing so, the water goes through different forms: liquid, solid and vapor. The ocean plays a key role in the water cycle as it is the source of 86% of global evaporation. [2]
Evaporation: the movement of water directly to the air from sources such as the soil and water bodies. It can be affected by factors including heat, humidity, solar radiation and wind speed. [6]: Ch. 1, "Evaporation" Transpiration: the movement of water from root systems, through a plant, and exit into the air as water vapor.
The US data is collected and compiled into an annual evaporation map. [4] The measurements range from under 30 to over 120 inches per year. Formulas can be used for calculating the rate of evaporation from a water surface such as a swimming pool. [5] [6] In some countries, the evaporation rate far exceeds the precipitation rate.
Pan evaporation is a measurement that combines or integrates the effects of several climate elements: temperature, humidity, rain fall, drought dispersion, solar radiation, and wind. Evaporation is greatest on hot, windy, dry, sunny days; and is greatly reduced when clouds block the sun and when air is cool, calm, and humid. [ 1 ]
The moist air has to be continually released to outside or else the air becomes saturated and evaporation stops. A mechanical direct evaporative cooler unit uses a fan to draw air through a wetted membrane, or pad, which provides a large surface area for the evaporation of water into the air. Water is sprayed at the top of the pad so it can ...
A specific application of rising tube evaporators is the thermal desalination of sea water. Sea water is pumped into the long tubes of the evaporator while the heating media (usually steam) heats it up. As vapour forms inside the tubes it flows upwards. This evaporation occurs under vacuum conditions that allow for the use of lower temperatures.