Incident surface, energy absorption

In the case of sound, the absorption coefficient (which is also called the acoustical absorptivity) is defined as the fraction of the incident sound energy absorbed by a surface or medium. the surface being considered par of an infinite area. 

Figure 3. Except for the latent heat of condensation released at the transparent surface, they all are forms of energy loss. Of primary significance in design and in evaluation of performance is the energy balance drawn around the distiller basin. This input is seen to be the incident solar energy minus reflection from the cover and the very small absorption in the cover. The feed water might also be considered a sensible heat supply, but it would usually be cooler than the product streams, and hence at a convenient base temperature, having zero energy input.

The term Qsh is the net solar radiant energy absorption rate on the basin bottom. It is equivalent to total radiation incident on the basin cover minus reflection from the cover, the water surface, and the basin bottom, and minus loss due to structural shadowing. Its determination from Weather Bureau records of total daily radiation on a horizontal surface is complicated by many factors such as variation in angle of incidence, and resulting transmissivity of cover, hourly and seasonally, intensity change due to cloudiness, and different properties of direct and diffuse radiations. Detailed explanation of these meteorological and optical calculations is beyond the scope of this paper, but may be found in the literature (6). 

The hemispherical total absorptivity is not only a property of the absorbing surface. Rather, it depends on the spectral distribution of the incident radiation energy. This is shown by the different values of a for the mainly short-wave solar radiation, in which the absorption properties at small wavelengths are decisive, and for the incident radiation from an earthly source, for which the long-wave portion of the absorption spectrum a (X,T) is of importance. 

Energy absorption at the incident surface, RQ quantaxl0 n g Gel content interval ... 

Because the energy distribution in the incident radiation depends upon the temperature and character of the originating surface, the absorptivity of the receiving surface may also depend upon these properties of the originating surface. 

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