title: Venus: new microwave measurements show no atmospheric water vapor.
abstract: Two sets of passive radio observations of Venus-measurements of the spectrum of the disk temperature near the 1-centimeter wavelength, and interferometric measurements of the planetary limb darkening at the 1.35-centimeter water vapor resonance-show no evidence of water vapor in the lower atmosphere of Venus. The upper limit of 2 x 10(-3) for the mixing ratio of water vapor is substantially less than the amounts derived from the Venera space probes (0.5 x 10(-2) to 2.5 x 10(-2)). This amount of water vapor cannot produce dense clouds, and it is doubtful that it may contribute significantly to a greenhouse effect.
authors.forename: M A
authors.initials: MA
authors.lastname: Janssen
authors.forename: R E
authors.initials: RE
authors.lastname: Hills
authors.forename: D D
authors.initials: DD
authors.lastname: Thornton
authors.forename: W J
authors.initials: WJ
authors.lastname: Welch