Estimation of surface temperature variations due to changes in sky and solar flux with elevation

Sky and solar radiance are of major importance in determining the ground temperature. Knowledge of their behavior is a fundamental part of surface temperature models. These two fluxes vary with elevation and this variation produces temperature changes. Therefore, when using thermal-property differences to discriminate geologic materials, these flux variations with elevation need to be considered. From a representative set of field observations, it was found that flux variations with elevation can cause changes in the mean diurnal temperature gradient from −4° to −14°C per km evaluated at 2000 m. Changes in the temperature-difference gradient of 1°-2°C per km are also produced which is equivalent to an effective thermal-inertia gradient of 100 W s^1/2 m⁻² K⁻¹ per km. Thus, exposed bedrock on topographic ridges will appear to have a lower thermal inertia due to the additional effect.