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Composition of the upper clouds of Venus
Author(s) -
Rea Donald G.
Publication year - 1972
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1029/rg010i001p00369
Subject(s) - venus , occultation , altitude (triangle) , atmospheric sciences , cloud top , atmosphere of venus , materials science , geology , environmental science , astrophysics , physics , astrobiology , astronomy , geometry , satellite , mathematics
Recent developments have shed new light on the composition of the upper Venus clouds. An analysis of the Mariner 5 occultation data has led to improved temperature and pressure profiles. When these are combined with transit data, it is concluded that there is an optically thin cloud layer with a top at 81‐km altitude where the temperature and pressure are, respectively, 175°K and 3 mb. The inclusion of temperatures derived from the near‐infrared CO 2 bands leads to the postulate of a second cloud deck with a top at 61‐km altitude, where T = 260°K and P = 240 mb. Additional important constraints on cloud models are imposed by the measured abundances of HCl and H 2 O, by the polarization data, and by the reflection and emission spectra. It is concluded that the leading candidate for the uppermost clouds is liquid drops of HCl‐H 2 O, that there is no recommended candidate for the second cloud deck, and that H 2 O ice is at most a minor component of these cloud systems.