Distribution of the relative brightness of quiet Sun regions at 350 μm observed bythe James Clerk Maxwell telescope by Lindsey et al. (1995) and analyzed by Judge et al. (2012). The radiance emitted at 350 μm originates close to the temperature minimum of the solar atmosphere structure. The relative brightness 1.00 corresponds to the median of the frequency distribution, which is set as equal to the radiance of the model F99-C at 350 μm, as this model successfully reproduces the present day quiet Sun (Shapiro et al. 2010). The radiance calculated with model F99-A, model VAL-B, and model PW-B is indicated relative to model F99-C. The relative brightness of model VAL-B is placed as given by Judge et al. (2012), whereas the the other indicated locations have been obtained from the relative radiance obtained from NLTE computations with NESSY.