A Model to Investigate the Effect of Evaporative Cooling on the Pattern of Evaporation in Sub-stomatal Cavities

A model has been developed to investigate the pattern of water evaporation from sub-stomatal cavities. In this model equations for the flux of matter are coupled to equations for the flux of heat. Failure to couple heat and mass transfer processes in previous models may have led to erroneous conclusions regarding the pattern of evaporation in sub-stomatal cavities. Our model predicts that the coolest surfaces are likely to be 0.1–0.4 °C cooler than the warmest surfaces. Evaporative cooling does alter the pattern of evaporation in sub-stomatal cavities, yet 63 to 80 per cent of all evaporation still occurs from a peristomatal region occupying about 4 per cent of the total sub-stomatal surface area.