Energy solar radiation

Relatively little of the atmosphere s mass is located above the troposphere, but the chemistry that occurs there is nonetheless crucial to maintaining life on earth. Particularly important is what takes place in the ozone layer, an atmospheric band stretching from about 20-40 km above the earth s surface. Ozone (03) is a severe pollutant at low altitudes but is critically important in the upper atmosphere because it absorbs intense ultraviolet radiation from the sun. Even though it is present in very small amounts in the stratosphere, ozone acts as a shield to prevent high-energy solar radiation from reaching the earth s surface, where it can cause such problems as eye cataracts and skin cancer. 

Ozone is produced by the reaction of short-waved, high-energy solar radiation with dioxygen. Light quanta with wavelengths < 242 nm split 02-molecules into two oxygen atoms which react with further oxygen molecules to produce ozone [4] ... 

The average daily incident solar radiation, or insolation, that strikes the earth s surface worldwide is about 220 W/m (1675 Btu/ft ). The annual insolation on 0.01% of the earth s surface is approximately equal to all energy consumed (ca 1992) by humans in one year, ie, 321 x 10 J (305 X 10 Btu). In the United States, the world s largest energy consumer, annual energy consumption is equivalent (1992) to the insolation on about 0.1 to 0.2% of U.S. total surface. 

The maximum efficiency with which photosynthesis can occur has been estimated by several methods. The upper limit has been projected to range from about 8 to 15%, depending on the assumptions made ie, the maximum amount of solar energy trapped as chemical energy in the biomass is 8 to 15% of the energy of the incident solar radiation. The rationale in support of this efficiency limitation helps to point out some aspects of biomass production as they relate to energy appHcations. 

Because water of depths below about 2 m does not absorb much solar radiation direcdy, the radiation is absorbed and converted to heat primarily in the basin floor, which thus should have high radiative absorptance in the solar radiation spectmm. It is also noteworthy that if the stUl is designed to have low heat losses to the ambient, and if the ambient temperature drops, distillation will continue for some time even in the absence of solar energy input, because the saline water may remain warmer than the condensing glass surface and thus continue evaporating. 

The ocean is an integral part of the climate system. It contains almost 96% of the water in the Earth s biosphere and is the dominant source of water vapour for the atmosphere. It covers 71% of the planet s surface and has a heat capacity more than four times that of the atmosphere. With more than 97% of solar radiation being absorbed that falls on the surface from incident angles less than 50" from the vertical, it is the main store of energy within the climate system. 

The sun radiates approximately as a blackbody, with an effective temperature of about 6000 K. The total solar flux is 3.9 x 10 W. Using Wien s law, it has been found that the frequency of maximum solar radiation intensity is 6.3 x 10 s (X = 0.48 /rm), which is in the visible part of the spectrum 99% of solar radiation occurs between the frequencies of 7.5 X 10 s (X = 4/um) and 2 x 10 s (X = 0.15/um) and about 50% in the visible region between 4.3 x 10 s (X = 0.7 /rm) and 7.5 X 10 s (X = 0.4 /Ltm). The intensity of this energy flux at the distance of the earth is about 1400 W m on an area normal to a beam of solar radiation. This value is called the solar constant. Due to the eccentricity of the earth s orbit as it revolves around the sun once a year, the earth is closer to the sun in January (perihelion) than in July (aphelion). This results in about a 7% difference in radiant flux at the outer limits of the atmosphere between these two times. 

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