The existence of downwelling long wave radiation DLR from the atmosphere to the Earth surface is supposedly evidenced by radiometers such as pyrgeometers and bolometers and by direct estimation of the emissivity of the atmosphere by a formula depending on temperature and vapor pressure, in both cases with coefficients determined by calibration with some chosen reference.
A pyrgeometer determines DLR as
- DLR = U_emf/S + sigma x T^4 with T the temperature of the instrument,
- DLR = (0.605 + 0.0048 x e^0.5) sigma T^4,
We see that in both cases DLR is determined from an ad hoc Ansatz of a certain form with certain coefficients to be determined by certain calibration. We understand that the Ansatz defines DLR ad hoc by formula and calibration, but the physical nature of DLR remains hidden since the Ansatz is ad hoc without physical basis.
Note that both formulas include Stefan-Boltzmann laws only valid in a surrounding of 0 K, which is not the case, and thus are ad hoc False Stefan-Boltzmann laws without physical meaning.