Enhance visible radiance was found in clear-air fields of view near a broken cloud, in the OCTS measurements. No meaningful change in the corresponding brightness temperature was observed, so the enhanced radiance is thought to be due to the effects of clouds near the fields of view (FOV). If a broken cloud exists in the vicinity of the FOV, the solar radiation reflected from the solar side of the cloud enters the FOV and may enhance the measured radiance. An increase of about 5% in the radiance clouds was measured by comparing it with the radiance in a region 10 km from the cloud at a wavelength of 0.412 μm. The enchanced radiance measured by the OCTS sensor almost coincides with the Monte-Carlo simulation.