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
Superheated water Superheated water Superheated water is liquid water under pressure at temperatures between the usual boiling point, and the critical temperature, . It is also known as "subcritical water" or "pressurized hot water." Superheated water is stable because of overpressure that raises the boiling point, or by heating it in a sealed vessel with a headspace, where the liquid water is in equilibrium with vapour at the saturated vapor pressure. This is distinct from the use of the term superheating to refer to water at atmospheric pressure above its normal boiling point, which has not boiled due to a lack of