Radiative properties

Touloukian, Y.S., and DeWitt, D.P. (1972), Thermal Radiative Properties of Non-metallic Solids, in Thermophysical Properties of Matter, Plenum, New York, pp. 3a-48a. 

In comparing the radiative properties of materials to those of a blackbody, fhe terms absorptivity and emissivity are used. Absorptivity is the amount of radiant energy absorbed as a fraction of the total amount that falls on the object. Absorptivity depends on both frequency and temperature for a blackbody if is 1. Emissivity is the ratio of the energy emitted by an object to that of a blackbody at the same temperature. It depends on both the properties of fhe subsfance and the frequency. Kirchhoff s law states that for any substance, its emissivity at a given wavelength and temperature equals its absorptivity. Note that the absorptivity and emissivity of a given substance may be quite variable for different frequencies. 

Hence, the radiative equilibrium temperature is sensitive to changes in the solar constant, planetary albedo, and the radiative properties of the earth-atmosphere-ocean system. In addition, changes internal to the earth-atmosphere-ocean system may alter the climate. Table I is an incomplete list of phenomena that individually or in concert could alter climate. 

The determination of electronic quantities is preliminary to the study of molecular dynamics and radiative properties. 

Atmospheric trace gas chemistry is a new rapidly growing field of paleo-atmospheric research, because the radiative properties of CO2, CH4, and N2O make them potential indicators of climate change. A fundamental problem in constructing a record of trace gas concentrations from ice-cores is the fact that the air in bubbles is always younger than the age of the surrounding ice. This is because as snow is buried by later snowfalls and slowly becomes transformed to fim and ice, the air between the snow crystals remains in contact with the atmosphere until the air bubbles become sealed at the fim/ice transition, when density increases to about 0.83gcm. The trapped air is thus younger than the matrix, with the age difference... 

Clarke, A. D., and R. J. Charlson, Radiative Properties of the Background Aerosol Absorption Component of Extinction, Science, 229, 263-265 (1985). 

The largest uncertainties are associated with the aerosol radiative properties (3, aIUI, and /RH, which is particularly sensitive to the treament of the dependence on relative humidity (vide infra), and with the amount of sulfate (i.e., in Bso2-) available to scatter light. Other sensitivity analyses also suggest that uncertainties in ysuir,llt, and rsuiratc, and hence in as... 

Andronache, C., L. J. Donner, V. Ramaswamy, C. J. Seman, and R. S. Hemler, The Effects of Atmospheric Sulfur on the Radiative Properties of Convective Clouds A Limited Area Modeling Study, Geophys. Res. Lett., 25, 4423-1426 (1998). 

King, M. D., Radiative Properties of Clouds, in Aerosol-Cloud-Climate Interactions (P. V. Hobbs, Ed.), pp. 123-149, Academic Press, San Diego, 1993. 

Tegen, I., and A. A. Lacis, Modeling of Particle Size Distribution and Its Influence on the Radiative Properties of Mineral Dust Aerosol, J. Geophys. Res., 101, 19237-19244 (1996). 

Sc(OEP)C>2CMe is 0.4 s, which is the longest for any porphyrin, while the fluorescent yield of 0.2 is very high. The radiative properties are explained in terms of covalent interactions between the metal and the ring as modified by the probable location of the metal ion above the porphyrin plane.24 Scandium OEP complexes are reduced to the a, y-dihydro derivatives on reduction with sodium anthracenide and methanol.25 The redox potentials of Sc(OEP)OH have been determined by cyclic voltammetry to be ligand oxidation in PrCN, 1.03 and 0.70 ligand reduction in DMSO, —1.54 (Ey2 values in V vs. SCE) no metal redox wave was observed.26... 

The effects of limited molecular flexibility and increasing deviation from coplanarity of the anthracene and ethylene ir-systems on the radiative properties have been assessed in a series of symmetrically 2,2-substituted l-(9-anthryl)ethylenes 87 [63]. As for structurally rigid 9-anthrylethylenes 88 and 89, for which rotation about the anthryl-ethylene single bond is not possible, and in which the ethylene double bond has been forced to be coplanar with the anthracene -system, their fluorescence quantum yields in cyclohexane are exceptionally high, i.e., 0.94 and 0.96, respectively, and the Stokes shifts are less than 200 cm 1 (see Figure 15). For nonplanar 9-vinylanthracene 87a and its dimethyl derivative 87b, whose ethylene double bond may be twisted out of the plane of the anthracene by about 60°, the quantum yield is 0.63, and the Stokes shifts are around 1000cm-1 (see Table 16). 

In Chapter 3 we considered briefly the photoexcitation of Rydberg atoms, paying particular attention to the continuity of cross sections at the ionization limit. In this chapter we consider optical excitation in more detail. While the general behavior is similar in H and the alkali atoms, there are striking differences in the optical absorption cross sections and in the radiative decay rates. These differences can be traced to the variation in the radial matrix elements produced by nonzero quantum defects. The radiative properties of H are well known, and the radiative properties of alkali atoms can be calculated using quantum defect theory. 

Morcrette, J.-J. (1991) Radiation and cloud radiative properties in the ECMWF forecasting system. J. Geophys. Res. 96, pp. 9121-9132. 

One of the earliest models for estimating the radiative properties of hot and dense plasmas was the average atom model introduced by Rozsnai [121]... 

Radiative influences of aerosols on climate are generally distinguished as direct, referring to scattering and absorption of radiation by the aerosol particles themselves, and indirect, referring to the influence of aerosols on the radiative properties... 

Brenguier J.-L. Pawlowska H. and Schuller L. (2003). Cloud microphysical and radiative properties for parameterization and satellite monitoring of the indirect effect of aerosol on climate. J. Geophys. Res., 108(D15), CMP6/1-CMP6/14. 

CCN). Changes in the concentrations of CCN may alter the cloud droplet concentration, the droplet surface reflectivity, the radiative properties of clouds (cloud albedo) (2), and hence, the earth s climate (8-101. This mechanism has been proposed for the remote atmosphere, where the radiative properties of clouds are theoretically predicted to be extremely sensitive to the number of CCN present (ID). Additionally, these sulfate particles enhance the acidity of precipitation due to the formation of sulfuric acid after cloud water dissolution (11). The importance of sulfate aerosol particles to both radiative climate and rainwater acidity illustrates the need to document the sources of sulfur to the remote atmosphere. 

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