SIO Reference 60-29. When sky spectral radiance measurements which were made during operational tests of a spectroradiometer were compared it was seen that there was a close relationship between the value of spectral radiances and. relative humidities.

SIO Reference 60-12. The Vieibllity Laboratory has instrumented a B-29 aircraft for documentation of the optical properties of the atmosphere within the visible spectrum. Two of the instruments are hemispherical scanners, one for the upper hemisphere and one for the lower hemisphere. These scanners measure the luminance of the upper and lower hemispheres.