The automatic interplanetary stations Venera 5 and Venera 6 reached Venus on May 16 and 17, respectively, and made measurements of the nightside atmosphere in the equatorial plane at a distance of 2700 km from the dawn terminator. The most probable distance between the points where the stations entered the atmosphere was about 300 km. The detailed description of the probe design may be found in Pravda .
The present paper analyses parameters of the planetary atmosphere based on the results of the direct measurements of pressure and temperature. A tentative model of the atmosphere can be constructed on the basis of the Venera 5 and Venera 6 in-situ measurements together with the earlier results of Venera 4 [Avduevsky et al., 1968, 1969] and Mariner 5 [Kliore et al., 1969].