Vapour-pressure deficit temperature, the relative humidity and, if possible, the canopy air temperature. We must then compute the saturation pressure. Saturation pressure can be looked up in a psychrometric chart or derived from the Arrhenius equation, a way to compute it directly from temperature is where: To convert between Rankine and degrees Fahrenheit: formula_10 We compute this pressure for both the ambient and canopy temperatures. We then can compute the actual partial pressure of the water vapour in the air by multiplying by the relative humidity [%]: and finally VPD using formula_12 or formula_13 when the canopy temperature is known. Vapour-pressure deficit
Mercury vapour turbine Mercury vapour turbine A mercury vapour turbine is a form of heat engine that uses mercury to drive the thermal cycle. A mercury vapour turbine has been used in conjunction with a steam turbine for generating electricity. This example of combined cycle generation does not seem to have been widely adopted, probably because of high capital cost and the obvious toxic hazard if the mercury leaked into the environment. The mercury cycle offers an efficiency increase compared to a steam-only cycle because energy can be injected into the Rankine cycle at higher temperature. Metallurgical developments have allowed steam-only plants to