Effect of aerosol on the radiation field in the mesosphere

The turbidity and relative variability of single-scattering brightness in the atmosphere at heights of 60-100 km are examined on the basis of rocket measurements. Calculations show that, in optically quiet conditions in the absence of noctilucent clouds, the increase in atmospheric brightness as compared with a purely molecular atmosphere does not exceed several tenths of a percent. The presence of noctilucent clouds determines a 10-20-percent brightness increase at a height of 85 km. Finally, an effort is made to explain the divergence between optical measurements made with the direct aerosol sampling technique and measurements made with other techniques.