Measurements made by a balloon-borne, single dispersion spectromter have been used to investigate the attenuation of solar irradiance in the wavelength region of the O2 Schumann-Runge bands and the Herzberg continuum. The data cover the altitude range from 28 to 39 km. The fine spectral resolution (0.012 nm) allows transmittance windows in the Schumann-Runge system to be resolved, facilitating the comparison of their characteristic absorption to model calculations. An atmospherically derived O2 cross section developed in this analysis is significantly lower than the Herzberg continuum values most used in photochemical models.