Water vapor in the Venus middle atmosphere

It is proposed that recent observations of water vapor abundances near 95 km altitude support the hypothesis that the aerosol particles in the upper haze layer of the Venus atmosphere are primarily concentrated sulfuric acid. Encrenaz et al. (1995) assumed the aerosol particles near 95 Irm altitude were water ice and inferred the temperature at that altitude was 140 +/- 10 K. Their observations, however, may also be consistent with saturated water vapor over 70 - 75 wt% sulfuric acid for temperatures near the nominal 160 - 170 K. These two interpretations lead to significantly different predictions regarding the escape rate for hydrogen. (C) 1999 COSPAR. Published by Elsevier Science Ltd.