Various tentative models for an atmospheric canopy of water in vapor or other form, as well as proposed extraterrestrial sources of water or ice, have had four purposes in the overall creation-flood model of origins. These have been explanation of a pre-flood semitropical climate, provision of substantial waters for the flood, explanation of glacial action and catastrophic freezing after the flood, and possible reduction in the pre-flood rate of carbon-14 production. The usual aim has been to provide explanations which involve only natural forces without divine miraculous intervention. Critical analysis of these models shows that the provision of a substantial part of flood waters or of ice either from a canopy or from extraterrestrial sources is impossible apart from special divine miraculous intervention. All of the models fail to meet the requirements of the laws of physics and/or physiology. Preliminary guidelines for the quantitative modeling of a limited water vapor canopy are offered.