The Venera 13 and Venera 14 spectrophotometry experiments

Spectrophotometers aboard the Venera 13 and Venera 14 landers recorded spectra of the solar radiation in the 0.45-1.2 micron wavelength range arriving along six different directions at all heights from 62 km down to the surface. The intensity of the 0.7-1 micron wavelength H2O bands yields water vapor abundances ranging from 10-20 ppm near the surface to an order of magnitude greater at H approximately 40 km. The H2O mixing-ratio profile, with its peak between 40 and 60 km, is in rough agreement with Venera 13 and 14 H2O abundance measurements obtained by other methods. A photometer with a 0.37 micron wavelength filter has furnished profiles for the ultraviolet-radiation intensity, indicating that 90 percent of the sunlight in this range is absorbed by clouds above the 58-km level.