Thermal inertia,thermal admittance,and the effect of layers

The effect of a diurnally varying flux on a solid surface is analysed in terms of thermal admittance, the reciprocal of complex thermal conductance. The presence of a surface layer of differing thermal characteristics from the bulk material, which can significantly affect the phase and amplitude of the temperature wave of the exposed surface, is discussed in terms of the admittance concept. It is suggested that the latter concept provides a better approach to the characterization of solid surfaces, particularly in the remote sensing context where varying water contents or organic materials are involved.