dˈuː tə mˈɛʒɚmənt kənstɹˈeɪnts, ɪɾ ɪz ˈɔfən ɡˈɪvən fɚðə spˈɛktɹəm ɪnwˌɪtʃ mˈoʊst sˈoʊlɚɹ ˈɛnɚdʒi ɹˈiːtʃᵻz ðə sˈɜːfɪs bᵻtwˌiːn zˈiəɹoʊ.θɹˈiː ænd θɹˈiː mjˈuːm.
Due to measurement constraints, it is often given for the spectrum in which most solar energy reaches the surface (between 0.3 and 3 μm).