Experimental testing of correlations to calculate the atmospheric “transparency window” emissivity coefficient

An experimental verification of the correlations existing in literature for the calculation of the coefficient of emissivity inside the atmospheric transparency window, situated in the wavelength band 8-14 μm, has been performed. In addition, the authors propose a new correlation for the calculation of the coefficient εin, easily applicable since it presupposes the knowledge of the global emissivity of the sky, for which there are a lot of correlations in literature.