Specularly reflecting spherical

For some typical modes of scattering from large spherical particles (f >5), simple formulations of phase functions can be obtained. These modes include scattering from a specularly reflecting sphere, scattering from a diffuse reflection sphere, and scattering by diffraction from a sphere. 

Figure 4.25. Optical diagram of DRIFTS accessory (1) flat mirror (50 x 50 mm), (2) flat mirror (70 X 70 cm), (3) concave spherical reflector, and (4) sample cell D = diffuse reflection S = specular reflection. Dashed lines show optical path of diffuse reflection. Solid bold line shows optical path of specular reflection. Reprinted, by permission, from B. Li and R. D. Gonzalez, Appl. Spectrosc. 52, 1488-1491 (1998), p. 1489, Fig. 1. Copyright 1998 Society for Applied Spectroscopy.

A 50-liter liquid nitrogen container is constructed of concentric copper spheres separated by a vacuum space. If the emissivities of both inner surfaces of the vacuum space are 0.018, what loss in liters per day of the contents and percent of rated contents per day would be expected just due to radiation heat transfer Assume specular reflection for the surfaces. The warm outer surface is at 300 K. What is the heat transfer by molecular conduction when the gas in the vacuum space is air at a pressure of 15 mPa measured at 300 K The area ratio of the inner to the outer spherical shells may be assumed to be 0.8. 

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