Accession Number : AD0619653

Title :   TRANSIENT RADIATIVE COOLING OF A SEMIINFINITE SOLID WITH PARALLEL-WALLED CAVITIES,

Corporate Author : BOEING SCIENTIFIC RESEARCH LABS SEATTLE WASH GEO-ASTRO PHYSICS LAB

Personal Author(s) : Winter,D. F.

Report Date : JUN 1965

Pagination or Media Count : 30

Abstract : A semi-infinite solid of blackbody material is separated into slabs by periodically spaced infinitely deep cavities bounded by plane parallel walls. The solid material is brought to uniform initial temperature and subsequently is allowed to cool by conduction in the interior and by radiation at the surfaces. The temperature history of the solid with cavities was calculated numerically. Similar calculations were performed to obtain the rate of cooling of the same material without cavities. Comparison is made between the apparent brightness temperatures measured at a great distance by a thermal radiation detector with a resolving power insufficient to discriminate between a smooth surface and one with cavities. It is shown that over a wide range of aspect angles the solid with cavities may have a higher apparent temperature even when the top surfaces of the slabs are cooler than the surface of a homogeneous solid. Phenomena such as the one described may be useful in the interpretation of measurements of infrared radiation from the lunar surface. (Author)

Descriptors :   (*BLACKBODY RADIATION, COOLING), (*MOON, INFRARED RADIATION), (*INFRARED RADIATION, MOON), THERMAL RADIATION, SURFACE PROPERTIES, SOLIDS, BRIGHTNESS, TEMPERATURE

Distribution Statement : APPROVED FOR PUBLIC RELEASE