I. The Thermal Conductivity Measurements of Selected Silicate Powders in Vacuum from 150° to 350° K. II. An Interpretation of the Moon's Eclipse and Lunation Cooling as Observed through the Earth's Atmosphere from 8-14 Microns

Citation

Watson, Kenneth (1964) I. The Thermal Conductivity Measurements of Selected Silicate Powders in Vacuum from 150° to 350° K. II. An Interpretation of the Moon's Eclipse and Lunation Cooling as Observed through the Earth's Atmosphere from 8-14 Microns. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/7HDE-1M52. https://resolver.caltech.edu/CaltechETD:etd-11042002-153232

Abstract

An apparatus was constructed to measure the thermal conductivity of powders in vacuum from 150° to 350°K. It was found that the conductivity of selected silicate powders can be adequately represented, within the experimental errors, by a temperature independent term related to the contact conduction plus a temperature cube term which is due to radiative transfer between and through the grains. The conductivity for glass spheres approximately suggests an inverse grain size dependence and does not appear to be related in any simple manner to the elastic contact area between the spheres. The effects of angular grains, produced by crushing, and limited chemical composition range are not significant when compared with the experimental errors. The radiative transfer term which is grossly independent of chemical composition and grain texture is dominated by radiation between the grains for grain sizes > 300 μ. Radiation through the grains is significant for grain sizes < 100 μ.

Previous interpretations of the eclipse observations of Pettit and Nicholson indicate that homogeneous constant thermal property models provide an adequate fit. The recent lunation observations of Murray and Wildey cannot be adequately explained by homogeneous models with either constant thermal properties or with thermal properties which are based on the results of this experimental investigation and existing specific heat data. It is suggested that the possibility of layering can best be examined in the region of the morning terminator.

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