Fig. 1.
Schematic of a leaf and an aluminium reference energy budget in the enclosed area of a phenotyping platform. The aluminium reference was painted black and had an emissivity (ε) of 0.96 to act as a reference for leaf energy balance assessment. Each arrow represents an energy flux, with the arrow direction representing either an input or output of energy. Symbol definition: σ, Stefan–Boltzmann constant; Tleaf, leaf temperature; Twall, wall temperature; Tref, aluminium reference temperature; Tair, air temperature; I(dir), direct irradiance; I(dif), diffuse irradiance; αl, leaf absorbance to shortwave irradiance; αr, reference absorbance to shortwave irradiance; gbh, boundary layer conductance to heat transfer; ρ, air density; Cs, specific heat capacity of humid air; E, leaf transpiration. Factor 2 in the equations represent the input or output energy for the two sides of the leaf/reference.