The structure of the lower atmosphere of Venus

Abstract

Belton et al. [1967] have recently presented the results of a spectroscopic analysis of the Venus atmosphere in the ‘region of line formation,’ which seems to be somewhat below the visible cloud tops. The term ‘clouds’ seems rather inappropriate; the scattering mean free path is so long (more than a kilometer) as to give the impression of a rather thin haze. The analysis also gives the temperature and an estimate of the gas pressure. Preliminary announcements have been made of the results obtained by the USSR dropsonde Venus 4, including, in particular, two more pressure-temperature points, one believed to be at the surface [Tass, 1967]. The dominant constituent was stated to be CO2, a result already surmised as a strong possibility on the basis of our optical measurements. The purpose of this note is to interpolate between these points, in pairs, to find temperature lapse rates and heights. The lapse rate is found to be approximately adiabatic for the lower interval, and strongly subadiabatic for the upper. The height of the line-forming region is around 40 km.