Solar radiation atmospheric pollution effect

Particles present in a polluted atmosphere exert further effects on climatic conditions. If their diameter is comparable with the wavelengths of the solar light, they are able to scatter the radiation. Larger particles partially absorb and partiaUy reflect the light. As a result of these phenomena, the mean annual intensity of solar radiation above polluted areas may be reduced by 15%. 

Pollutant effects on the atmosphere include increased parhculate matter, which decreases visibility and inhibits incoming solar radiahon, and increased gaseous pollutant concentrations, which absorb longwave radiation and increase surface temperatures. For a detailed discussion of visibility effects, see Chapter 10. 

This section is devoted to the results of some theoretical studies on solar radiation, absorption rates, and primary photochemical processes in smog, undertaken by Leighton (18). In work sponsored by the Air Pollution Foundation, Leighton made a critical analysis of the chemical effects that sunlight and sky radiation may have on smog formation in urban atmospheres. The radiant energy available for photochemical... 

From the foregoing parts of this book it is clear that solar radiation in the stratosphere is primarily attenuated by ozone (see Subsection 3.4.3) and at a lesser extent by the stratospheric sulfate aerosol layer (see Subsection 4.4.3). This means that any change in the stratospheric 03 burden or aerosol concentration involves modification of radiative transfer in this atmospheric domain. We should remember that the residence time of trace constituents above the tropopause is rather long because of the thermal structure and the absence of wet removal. Furthermore at these altitudes the density of the air is low as compared to that of lower layers. For this reason even an insignificant quantity of pollutants can produce relatively long and significant effects. 

Atmospheric Pollutants. Ozone is present in the earth s atmosphere both as a result of uv photolysis of oxygen in the upper atmosphere and as a result of reaction between terrestrial solar radiation and atmospheric pollutants such as nitrogen oxides and hydrocarbons from automobile exhausts. It is a powerful oxidant that can react rapidly with elastomers and other imsatin-ated polsrmeric materials to cause stiffening and cracking, particularly imder mechanical stress. Other common air pollutants include sulfur oxides, hydrocarbons, nitrogen oxides, and particulate matter such as sand, dust, dirt, and soot. Some of these may react directly with organic materials, but have a much more severe effect in combination with other weather factors. 

One possible reason for this rate enhancement, at least in some instances, is a change in absorption cross sections and/or photolysis quantum yields due to selfassociation at the interface. This effect has been documented for aromatic compounds both spectroscopically and by simulations [278, 282, 283], and is a consequence of the different hydrogen bonding environment present at the air-ice interface compared to the liquid surface. In the case of benzene in particular, the self association gives rise to a significant red-shift in the absorption spectrum [279], such that benzene present at the air-ice interface may absorb available solar radiation in the lower atmosphere. This opens the possibility of a previously unconsidered fate for several aromatic pollutants present in snow- and ice-covered regions. 

Solar systems are subjected to a unique set of conditions that may alter their stability and, hence, their performance and life-cycle costs. These conditions include UV radiation, temperature, atmospheric gases and pollutants, the diurnal and annual thermal cycles, and, in concentrating systems, a high-intensity solar flux. In addition, condensation and evaporation of water, rain, hall, dust, wind, thermal expansion mismatches, etc., may impose additional problems for the performance of a solar system. These conditions and problems must be considered not only individually, but also for synergistic degradative effects that may result from their collective action on any part of the system. Since these degradative effects may also reduce the system or component performance, protective encapsulation of sensitive materials from the hostile terrestrial environment is required to provide component durability. 

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