Spectral Transformities for SolarRadiation Reaching the Earth

Solar transformities were computed for the solar irradiance spectrum at the top of the Earth’s atmosphere, assuming a model in which the sun radiates as a blackbody with a temperature of 6000 K. Conventionally, the solar transformity (ST) of sunlight reaching the surface of the Earth’s atmosphere has been defined as one. Here, the ST of irradiance at the median wavelength, 794 nm, is defined as one. This prevents double-counting and presumes that emergy splits when allocated to each wavelength of radiation. Based on the assumption that the energy from the Sun’s thermonuclear reactions that produced ultraviolet radiation also produced visible light and infrared radiation, the ST for a specific wavelength was computed using the cumulative sum of energy at longer wavelengths. The ST of infrared radiation ranged between 0.1 and 1.3 sej/J, less than the range of solar transformities for visible light (1.0 – 2.0 sej/ J). The ultraviolet spectrum (100 – 400 nm) had solar transformities between 2.0 and 1.7 x10 sej/J. Xray radiation (0.225 – 0.45 nm) was found to have solar transformities between 1.3x10 and 1.5x10 sej/ J.