Heat of vaporization of water at 20˚C

Value 2.45 kJ/gram
Organism Generic
Reference Körner C (2013) Plant-environment interactions. Chapter 12, pp.1065-1166 in: Bresinsky et al. (eds) Strasburger's plant sciences. Springer Berlin Heidelberg p.1067 left column 2nd paragraph
Comments P.1067 left column 2nd paragraph: "Heat storage in leaves is negligible due to their small mass: Q=H+E, E=gΔw v, H=hΔT q, where g is the diffusive conductance of the leaf epidermis to water vapor (basically the conductance of the stomatal pores), Δw is the gradient of the molar mixing ratio of water vapor and air between the intercellular spaces inside the leaf and the free air around it (at sea level at 0.1 MPa air pressure, this corresponds numerically to the gradient of water vapor pressure), and v is the heat of vaporization of water (2.45 kJ/g at 20˚C)- h is the thermal conductance of the air layer at the surface of the leaf (a function of leaf width and wind speed), ΔT is the temperature difference between leaf and air, and q the heat capacity of air. Conductances are the reciprocals of the respective resistances (the resistances to water vapor diffusion and heat exchange)."
Entered by Uri M
ID 113225