770 36 Thermography to Measure Water Relations of Plant
Leaves
The transfer velocity kheat can be defined as the ratio of
the diffusion coefficient D to the diffusion length
∆x:
∆cwv is the difference between water vapor concentrations
inside the leaf and in the surrounding turbulent air. The concentrations
can be expressed as relative humidities (fractions of the water vapor
saturation concentration at the given temperature):
Equation (36.2) can now be expressed by the individual contributing
terms:
A 
leaf 
dt 

(36.15)

+2kleaf heatρ cp (Tair −
Tleaf) + kwv λ cwv (hleaf − hair)

� 
C
A 
+ 2αleaf IRσ�T4 ref− T 4
leaf�+ 2ρcp�kleaf heat−αleaf
αref IR IRkref heat�Tair
+ 2ρcp�αleaf αref IR
IRkref heatTref − kleaf
heatTleaf�+ jlat

