Solar deleterious effect

Ozone is a gas that occurs naturally in relatively large concentrations in the upper-atmospheric layer known as the stratosphere. The stratosphere is between 5-10.6 mi (8-17 km) to about 31 mi (50 km) above the earth s surface. Stratospheric ozone is very important to life on the surface of Earth because it absorbs much of the incoming solar ultraviolet radiation, and thereby shields organisms from its deleterious effects. Since the mid-1980s, there has been evidence that concentrations of stratospheric ozone are diminishing as a result of complex photochemical reactions involving chloroflno-rocarbons (CFCs). These persistent chemicals are synthesized by humans and then emitted to the lower atmosphere, from where they eventually reach the stratosphere and deplete ozone. 

Weathering Factors. The deleterious effect of wood weathering has been ascribed to a complex set of reactions induced by a number of factors (2). The weathering factors responsible for changes in the wood surface are as follows moisture (dew, rain, snow, and humidity), solar radiation (ultra-... 

Optical KLenents. Problems which are common to many solar-related optical elements Include dirt retention, cleaning, surface abrasion, and photodegradation. A common feature of some of these problems Is that the deleterious effects occur at an Interface. Ultraviolet radiation, atmospheric components, mechanical stress, etc., can have a profound effect on performance by changing surface characteristics. The lifetimes of UV stabilizers can be limited by exudation permeability can cause harmful reactions at Interfaces and mechanical properties can be Influenced by surface crazing. In other applications mechanical behavior of the bulk polymer Is critical and virtually all applications require that the polymer system withstand multiple environmental stresses simultaneously. 

The promise of photoelectrochemical devices of both the photovoltaic and chemical producing variety has been discussed and reviewed extensively.Cl,, 3,4) The criteria that these cells must meet with respect to stability, band gap and flatband potential have been modeled effectively and in a systematic fashion. However, it is becomirg clear that though such models accurately describe the general features of the device, as in the case of solid state Schottky barrier solar cells, the detailed nature of the interfacial properties can play an overriding role in determining the device properties. Some of these interface properties and processes and their potential deleterious or beneficial effects on electrode performance will be discussed. 

Because ozone selectively absorbs these deleterious wavelengths of solar radiation, it serves as an ultraviolet shield. As such, stratospheric ozone helps to protect humans and other organisms on Earth s surface from some of the harmful effects of exposure to this high-energy electromagnetic radiation, hi fact, without the protective action of the stratospheric ozone layer, it is likely that... 

---