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The temperature of a thin turbid layer above the ground is expressed as a function of time by considering the processes of nocturnal radiation and eddy conduction. It is found that under certain conditions the layer will cool until the lapse rate below the turbid layer becomes unstable. It is suggested that vertical mixing then may transform the thin layer into a thick layer extending to the ground. At the same time increased stability above the turbid layer may result in a sharply defined upper boundary. The temperature distribution in a thick turbid layer is found to depend on the free-air and ground temperatures (treated as constants), the infra-red absorptivity of the layer, and the eddy conductivities within and above the layer. If certain critical conditions are satisfied, the lapse rate within the turbid layer will become unstable and the lapse rate within the non-turbid air will become stable. Observations of the vertical temperature distribution before and after fog formation support thi...

A diffusion-deposition model is developed for use in estimating dosage levels due to inflight release of fission fragments from a nuclear-powered aircraft. The model is based on the work of Sutton for diffusion and the work of Chamberlain for deposition. The model considers an elevated instantaneous point source and an elevated instantaneous line source oriented at an arbitrary angle to the mean wind direction. Suggested values of the various deposition, rain-out and diffusion parameters to be used with the model are presented along with a qualitative discussion of the uncertainties of the model and the suggested parameters.