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The Penman equation describes evaporation (E) from an open water surface, and was developed by Howard Penman in 1948. Penman's equation requires daily mean temperature, wind speed, air pressure, and solar radiation to predict E. Simpler Hydrometeorological equations continue to be used where obtaining such data is impractical, to give comparable results within specific contexts, e.g. humid vs ...
The Penman-Monteith equation approximates net evapotranspiration (ET) from meteorological data as a replacement for direct measurement of evapotranspiration. The equation is widely used, and was derived by the United Nations Food and Agriculture Organization for modeling reference evapotranspiration ET 0.
Potential evapotranspiration (PET) or potential evaporation (PE) is the amount of water that would be evaporated and transpired by a specific crop, soil or ecosystem if there was sufficient water available. It is a reflection of the energy available to evaporate or transpire water, and of the wind available to transport the water vapor from the ...
Howard Latimer Penman (1909 – 1984) was a British meteorologist. He formulated Penman’s Formula, which is used worldwide by meteorologists and agricultural scientists to assess evaporation rates in different setups (lakes and ponds, lawns, cropped fields) and locations in the world. With John Monteith he formulated the Penman–Monteith ...
Definition. Evapotranspiration is defined as: "The combined processes through which water is transferred to the atmosphere from open water and ice surfaces, bare soil and vegetation that make up the Earth’s surface." [2]: 2908. Evapotranspiration is a combination of evaporation and transpiration, measured in order to better understand crop ...
A general water balance equation is: [5] P = Q + ET + ΔS. where. P is precipitation. Q is streamflow. ET is evapotranspiration. ΔS is the change in storage (in soil or the bedrock / groundwater) This equation uses the principles of conservation of mass in a closed system, whereby any water entering a system (via precipitation), must be ...
Condensing vapors from flash tank B1 heat evaporator A2. In chemical engineering, a multiple-effect evaporator is an apparatus for efficiently using the heat from steam to evaporate water. [1] Water is boiled in a sequence of vessels, each held at a lower pressure than the last. Because the boiling temperature of water decreases as pressure ...
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. [1] A high concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidity affects rate of evaporation of water. [2] When the molecules of the liquid collide, they transfer ...