Does spectroscopic evidence require two scattering layers in the Venus atmosphere.

Comments on Hunt's (1972) conclusion that the phase variation of lines in the 7820- and 7883-A CO2 bands is due to the presence of two scattering layers in the Venusian atmosphere. It is shown that the increase of equivalent width with phase between 0 and 90 deg noted by Hunt in the data by Gray Young et al. (1971) does not necessarily require a two-layer model of scattering in the Venusian atmosphere and that this increase may be due to the strong backward lobe in the Venusian cloud phase function. Hunt, in a reply, notes that Regas et al. incorrectly use in their analysis Hansen's (1969) data which are for a homogeneous planetary atmosphere, while Hunt used an inhomogeneous model of the Venusian atmosphere. In addition, further evidence to support Hunt's claim for a multilayered structure of the upper Venusian clouds is presented.