Energy distribution of solar radiation

Fig. 40 Energy distribution of solar radiation (according to CIE, No. 20) and filtered xenon arc light (Xenotest 1200) [102].

Leckner. B. (1978) The spectral distribution of solar radiation at the Earth s surface - elements of a model. Solar Energy.. 20, 143. 

Collares-Pereira M., Rabl A., The average distribution of solar radiation correlations between diffuse and hemispherical and between daily and hourly insolation values. Solar Energy 1979 22 155-164. 

Fig. 2. Ozone effect on solar radiation (left) and dependence of ozone concentration on atmospheric altitute (right). In the left part the dotted curve represents the photon distribution of solar energy outside the atmosphere (based on the assumption of black body radiation at T = 5773 K). The full curve gives the photon distribution of solar radiation reaching earth surface (see Ref.8. The ozone effect is shown by shadowed area, the dicline above 800 nm is mainly due to absorption by water vapour. On the right side the full curve represents qualitatively a typical ozone profile, the real ozone distribution significantly depends on the local situation (geography), see Ref.15)...

Figure 7.3a represents the Planck distribution for blackbody spectral emissive power with E-i p / as a function of XT. The band fraction of emitted energy in the region from 0 to XT is equal to the shaded area, which is expressed as and shown in Figure 7.3b. About a quarter of the emitted energy is at wavelengths shorter than nd nearly 95% of the emitted energy is distributed between and The spectral distribution of solar radiation can be...

The most decisive technical problem with respect to weathering devices is to achieve an adequate simulation of solar radiation. When artificial weathering first began in the 1920s, the only source of intense radiation available was the carbon arc. The spectral energy distribution of this radiation bears but a faint similarity to that of solar radiation. 

The spectral distribution of this radiation is given in Table 4.3, from which we can easily see that radiation with wavelengths below 150nm represents only a tiny fraction of the total. The energy distribution of the solar radiation corresponds to that from a black body with a temperature of around 5,000 K. 

The sun s total radiation output is approximately equivalent to that of a blackbody at 10,350°R (5750 K). However, its maximum intensity occurs at a wavelength that corresponds to a temperature of 11,070°R (6150 K) as given hy Wien s displacement law. A figure plotting solar irradiance versus spectral distribution of solar energy is given in Fig. 9. See also Solar Energy. 

Both these effects require knowledge of the spectral and spacial radiation distributions of the radiation flux on a surface. The determination of both these distributions at a given location is a difficult instrumentation problem. In this paper, the effect of scattering processes in the atmosphere on the available energy of solar radiation on a surface is examined. Both the spectral and spacial effects of Rayleigh scattering are demonstrated. 

Besides the absorption of the various components of solar irradiation, additional infrared (IR), or thermal, radiation is also absorbed by a leaf (see Eq. 7.2 and Fig. 7-1). Any object with a temperature above 0 K ( absolute zero ) emits such thermal radiation, including a leaf s surroundings as well as the sky (see Fig. 6-11). The peak in the spectral distribution of thermal radiation can be described by Wien s displacement law, which states that the wavelength for maximum emission of energy, A,max, times the surface temperature of the emitting body, T, equals 2.90 x 106 nm K (Eq. 4.4b). Because the temperature of the surroundings is generally near 290 K, A,max for radiation from them is close to... 

In solar energy applications, the spectral distribution of incident solar radiation is very different than the spectral distribution of emitted radiation by the... 

It is well known that the spectral distribution and irradiance of the solar radiation at the Earth s surface depend on the location and is subjected to seasonal and diurnal variations. Therefore, a reference spectrum is needed as a basis for comparison with the spectral energy distribution of artificial light sources. Data from CIE No. 15 1971 (colorimetry official recommendations of the International Commission on Illumination) that recommend a standard illuminant D65 with a scheduled color temperature of approximately 6500 K have been used as a basis over the years. 

Figure 5.1 Spectral energy distribution of global solar radiation according to CIE No. 85, Table 4 (1989).

Figure 10.123 shows the distribution of solar energy with the strengths of several chemical bonds included for reference. Over 50% of the sun s radiation has sufficient energy to break weak bonds such as O—O or N—N only about 5% of the total is sufficiently energetic to break a carbon-carbon bond,... 

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