Figure 1
From: The coherence time of sunlight in the context of natural and artificial light-harvesting
Solar spectral irradiance. The composite solar spectral irradiance curve (orange) compiled by Wehrli44 and the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center (WRC) is often cited as the standard extraterrestrial spectral irradiance. This curve is well approximated by a black-body at 5777 K at 1 AU (blue). The Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS) by Gueymard45 and hosted by the National Renewable Energy Laboratory (NREL), is used to model solar spectral irradiance on Earth’s surface. The yellow curve shows the Direct Normal Irradiance in Edinburgh, Scotland in May 2020 using SMARTS version 2.9.5. Compared to the extraterrestrial curve, the SMARTS irradiance shows noticeable atmospheric filtering, including the characteristic absorption bands of \(\text {O}_2\), \(\text {H}_{2}\text {O}\), and \(\text {CO}_2\). The purple window represents the 340–1100 nm spectral responsivity range for the silicon photodetector used to measure \(\Delta \tau _{Sun}\) in this work.
