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
Vapour Col Vapour Col Vapour Col is a col lying south of Stonethrow Ridge on the west side of Deception Island in the South Shetland Islands of Antarctica. The name given by the United Kingdom Antarctic Place-Names Committee (UK-APC) in 1959 originates from the fumaroles in the col. This is the only locality on Deception Island where there is a complete cross section through the stratigraphy of volcanic succession. A 148 tract of ice-free land rising steeply from the south-western shore of Deception Island to 340 m, and including Vapour Col, has been identified an Important Bird Area (IBA) by BirdLife International