Solar radiation visible

Solar radiation - visible light infrared (IR) radiation - UV radiation... 

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. 

Long-wave radiation (infrared radiation) is in the range of 0.8-100 i.m, short-wave radiation (visible as light) is in the range 0.4-0.8 [Lin, and solar radiation is in the range 0.3-3.0 juim. 

Radiation. Mainly by infrared waves (but also in the visible band, e.g. solar radiation), which are independent of contact or an intermediate fluid. 

The sensitizers display a crucial role in harvesting of sunlight. To trap solar radiation efficiently in the visible and the near IR region of the solar spectrum requires engineering of sensitizers at a molecular level (see Section 9.16.3).26 The electrochemical and photophysical properties of the ground and the excited states of the sensitizer have a significant influence on the charge transfer (CT) dynamics at the semiconductor interface (see Section 9.16.4). The open-circuit potential of the cell depends on the redox couple, which shuttles between the sensitizer and the counter electrode (for details see Section 9.16.5). 

Adding N-, O-, or S-atom functionalities to a PAH can cause major changes in its UV-visible absorption spectrum. For example, as seen in Fig. 10.12, addition of NO 2 groups to BaP to form the 1-, 3-, and 6-nitro isomers results in pronounced red shifts in their absorption spectra (Pitts et al., 1978). This enhanced ability to absorb solar radiation has significant implica-... 

In Chapter 3 we examined the interaction of incoming solar radiation in the UV and visible regions of the spectrum with atmospheric gases, which drives atmospheric photochemistry. This incoming solar radiation... 

Fluorescence is not useful simply for chemical analysis. For example, a fluorescent additive that sticks to textile fibres is added to laundry soap. This compound absorbs solar radiation in the non-visible part of the spectrum and re-emits at longer wavelengths in the blue spectral region, which makes clothing appear whiter. Another application of fluorescence encountered daily is cathode tube lighting. The internal walls of these tubes are covered with mineral salts (luminophores) that emit in the visible region due to excitation by electrons. 

A greenhouse gas is any component of tbe atmosphere that allows visible solar radiation to reach the Earth s surface but prevents invisible infrared radiation (beat) from escaping back into outer space. This mimics the warming action of a greenhouse. If it were not for the atmosphere s greenhouse effect, Earth s average surface temperature would be a chilly -i8°C. 

In 1800 Sir William Herschel found that a thermometer placed in the region beyond the red end of the solar spectrum (obtained by dispersing solar radiation with a prism) was heated even more than when placed in the visible portion Herschel had discovered infrared radiation. Around 1900 infrared (IR) absorption investigations of molecules began. 

Although the reaction in Eq. IS. 196 is potentially catalytic, true catalysis has rarely been achieved. However, when MV is [RMpopljl4-. solar-driven catalytic oxidation has been observed.3 1 In monometallic Pt(ll) complexes the HOMQ-LUMO transition is in the UV region with perhaps a tail into the violet. The complexes arc thus white or perhaps yellowish. The interaction present in bimetallic complexes, as shown in Fig. 15.50, narrows the HOMO-LUMO gap such that this transition may be shifted into the visible region. The electron may thus be excited by solar radiation ... 

The peak of the O2 photodissociation occurs in the stratosphere (near 35 km for an overhead sun) where the total number of 02 molecules pho-todissociated is of the order of 107 cm-3 sec-1. Below the ozone peak (<25 km) the photodissociation rate decreases rapidly, particularly when the solar zenith angle increases. Below 20 km, the atomic oxygen production becomes very small and there is no atomic oxygen production in the troposphere by the 02 photodissociation. The ozone photodissociation is the result of the absorption of solar radiation in the visible and the ultraviolet ... 

Covering a wide spectral range, solar radiation is divided roughly into two equal energy portions—the ultraviolet and visible in the 0.25- to 0.7-micron wave lengths, and the infrared out to about 2 or 2.5 microns. 

Ozone forms in the upper stratosphere from molecular oxygen under the influence of UV solar radiation. In the lower stratosphere and troposphere, the source of ozone is the decomposition of nitrogen dioxide under the influence of UV and visible radiation. The formation of the vertical profile of ozone concentration is connected with its meridional and vertical transport. The general characteristic of this profile is the total amount of ozone measured by the thickness of its layer given in Dobson units (1 DU = 0.001 cm). 

ADEOS An improved, satellite Earth-observing system equipped with modernized radiometer of the visible and near-IR intervals (AYNIR), ocean color and temperature scanner (OCTS), and radiometer POLDER to carry out global systematic measurements of polarization and spectral characteristics of solar radiation reflected by the Earth-atmosphere system. The satellite ADEOS-2/ Midori-2 was launched on December 14, 2002 by the Japan Space Agency and is an ideal means of global monitoring. 

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