 Contributions with wavelengths larger than 40 μm are small, therefore often only wavelengths up to 50 μm are considered .In the wavelength range between 4 μm and 10 μm the spectrum of outgoing long-wave radiation overlaps that of solar radiation, and for various applications different cut-off wavelengths between the two may be chosen.Radiative cooling by outgoing long-wave radiation is the primary way the Earth System loses energy.