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Showing papers on "Radiative transfer published in 1972"


Journal ArticleDOI
TL;DR: In this paper, separate wave equations with source terms are presented for electromagnetic and gravitational perturbations of an uncharged, rotating black hole, which describe the radiative field completely, and also part of the non-radiative field.
Abstract: Separable wave equations with source terms are presented for electromagnetic and gravitational perturbations of an uncharged, rotating black hole. These equations describe the radiative field completely, and also part of the nonradiative field. Nontrivial, source-free, stationary perturbations are shown not to exist. The barrier integral governing synchrotron radiation from particles in circular orbits is shown to be the same as for scalar radiation. Future applications (stability of rotating black holes, "spin-down," superradiant scattering, floating orbits) are outlined.

857 citations


Journal ArticleDOI
TL;DR: In this article, a comparison with five fluorescence field measurements, with full width at half-maximum measurements of $L\ensuremath{-}M$ x rays, and with Bhalla's relativistic radiative-yield calculations was made with five different fluorescence fields.
Abstract: Calculated Auger, Coster-Kronig, super Coster-Kronig, and radiative transition rates are used to compute atomic $M$-shell Auger, Coster-Kronig, and fluorescence yields. Comparison is made with five fluorescence-field measurements, with full width at half-maximum measurements of $L\ensuremath{-}M$ x rays, and with Bhalla's relativistic radiative-yield calculations.

470 citations


Journal ArticleDOI
TL;DR: In this paper, the total thermal conductivity (lattice plus radiative) of several important earth materials is measured in the temperature range from 500 to 1900 K. A new technique is used in which a CO2 laser generates a low-frequency temperature wave at one face of a small disk-shaped sample, and an infrared detector views the opposite face to detect the phase of the emerging radiation.
Abstract: The total thermal conductivity (lattice plus radiative) of several important earth materials is measured in the temperature range from 500 to 1900 K. A new technique is used in which a CO2 laser generates a low-frequency temperature wave at one face of a small disk-shaped sample, and an infrared detector views the opposite face to detect the phase of the emerging radiation. Phase data at several frequencies yield the simultaneous determination of the thermal diffusivity and the mean extinction coefficient of the material. The lattice, radiative, and total thermal conductivities are then calculated. Results for single-crystal and polycrystalline forsterite-rich olivines and an enstatite indicate that, even in relatively pure large-grained material, the radiative conductivity does not increase rapidly with temperature. The predicted maximum total thermal conductivity at a depth of 400 km in an olivine mantle is 0.020 cal/cm/sec/deg C, which is less than twice the surface value.

436 citations


Journal ArticleDOI
Peter Stone1
TL;DR: In this article, a simple model is developed in which the radiative flux of heat is assumed to be balanced by the fluxes of sensible beat and potential energy due to large-scale eddies.
Abstract: In order to obtain estimates of the static stability in rotating atmospheres without performing numerical integrations of the equations of motion, a simple model is developed in which the radiative flux of heat is assumed to be balanced by the fluxes of sensible beat and potential energy due to large-scale eddies. The radiative flux divergence is modeled by a linearization about the radiative equilibrium state and the dynamical fluxes are modeled by calculating correlations from stability theory and by assuming that the amplitudes are limited by nonlinear effects. From the energy equation a single algebraic equation is derived for the mean equilibrium value of the Richardson number, Ri, in the troposphere. The radiative equilibrium state is assumed to be known. Once the solution for RI is found, the mean vertical and meridional gradients of potential temperature, 〈∂θ/∂z〉 and 〈∂θ/∂y〉, and the main properties of the mean zonal wind and eddies can be easily calculated. Even though many important flu...

361 citations


Journal ArticleDOI
TL;DR: In this paper, the collisional-radiative recombination and ionization coefficients for hydrogen plasmas of low ionization degree were calculated for a coupled system of rate equations, which not only accounts for the electronic but also for the atomic collision processes.
Abstract: The collisional-radiative recombination and ionization coefficients have been calculated for hydrogen plasmas of low ionization degree. The method consists in solving a coupled system of rate equations which not only accounts for the electronic but also for the atomic collision processes.

286 citations


BookDOI
01 Jan 1972

231 citations


Journal ArticleDOI
TL;DR: In this paper, the polarisation dependence of light emitted at different angles from the surface of thin silver films is measured, and it is demonstrated that surface roughness is responsible for light emission and not bulk inhomogeneities of the silver film.

211 citations



Journal ArticleDOI
TL;DR: In this paper, the effects of line shape and band structure on the radiative equilibrium temperature profile in planetary atmospheres have been examined and a method for calculating radiative terms is developed which avoids the usual approximations.
Abstract: Numerical experiments are performed to examine the effects of line shape and band structure on the radiative equilibrium temperature profile in planetary atmospheres. In order to accurately determine these effects, a method for calculating radiative terms is developed which avoids the usual approximations. It differs from the more commonly used methods in that it allows arbitrary dependence of the absorption coefficient on wave number, without requiring tedious line by line integration and without the constraints of band models. The present formulation is restricted to homogeneous atmospheres but the concept can be extended to the more general case. The numerical experiments reveal that the line shape and band structure of the absorbing gases have a large effect on temperatures in the higher layers of the atmosphere (corresponding to the stratosphere and mesosphere). The more nongrey the spectrum (that is, the higher the peaks and the deeper the troughs in the spectrum), the lower the temperature.

152 citations


Journal ArticleDOI
TL;DR: In this article, the authors measured the irradiance of the solar beam on cloudless days at Sutton Bonington in the English Midlands and at sites in north-west Scotland and calculated the mean monthly values of T. at four Meteorological Office stations were calculated from records of solar radiation and hours of sunshine and corresponding values of total and diffuse flux were tabulated for isolated ’, ‘ rural ’ and ‘ urban ’ sites.
Abstract: SUMMARY The irradiance of the solar beam was measured on cloudless days at Sutton Bonington in the English Midlands and at sites in north-west Scotland. Total and diffuse fluxes were also measured on some days. An attenuation coefficient for aerosol T. was defined by S(T~) = S(o) exp ( - Ta m) relating the measured flux at normal incidence S(T.) to the Rux calculated for adust-free atmosphere when the air mass number is m. Changes of T. from day to day were related to changes of air mass origin; local sources of aerosol were relatively unimportant. In maritime air, ra ranged from 0.05 to 0.15, and in continental air, from 0.1 to 0.5. In a tropical maritime air mass, T~ decreased from 0.13 at sea level to 0.07 at 1,340 m. The fraction of (ultra-violet f visible) to total radiation was (0.54 - 0.28 7.) and the ratio of diffuse to total radiation (m < 2) was (0.1 + 0.7 7.). The ratio of total scattering to absorption by aerosol decreased from 4 at m = 1.1 to 0.5 at m = 2. Mean monthly values of T. at four Meteorological Office stations were calculated from records of solar radiation and hours of sunshine and corresponding values of total and diffuse flux were tabulated for ‘ isolated ’, ‘ rural ’ and ‘ urban ’ sites. The presence of solid particles in the Earth’s atmosphere has important consequences for the transmission of solar radiation and for the nature of the radiation rkgime at the ground. The absorption of solar energy by a layer of aerosol increases the radiative heating of the atmosphere and decreases the amount of energy available at the surface. Scattering by aerosol increases the amount of radiation which is reflected by the atmosphere into space and increases the downward flux of diffuse radiation at the Earth’s surface. Attenuation also produces changes in the spectral composition of solar radiation which are significant biologically. To estimate the amount of radiant flux which is absorbed and scattered by aerosol as distinct from other atmospheric constituents, measurements of direct and diffuse radiation at, the ground may be compared with the fluxes predicted below a model atmosphere containing appropriate amounts of ozone, water vapour, and carbon dioxide (G. D. Robinson 1962, 1966). The height distribution of aerosol can be inferred by measuring solar radiation from aircraft (Roach 1961), and the presence of particles as high as 50 km has been demonstrated by measuring the scattering of light from searchlight beams (Elterman, Wexler and Chang 1969). Concern about possible changes in global climate has stimulated new interest in the radiative effects of aerosol. Recent calculations by Rasool andSchneider (1971) imply that any future increases of aerosol content will decrease the mean surface temperature of the Earth and that the heat balance of the atmosphere may become increasingly sensitive to changes of aerosol content. To be able to detect the radiative effects of changing aerosol content, it is essential to establish baselines for the income of solar radiation in different parts of the world and to show how this income is related to aerosol load. This kind of exercise has been attempted at relatively few sites. Valko (1963) analysed turbidity measurements at LocarnoMonti in Switzerland and demonstrated marked daily and annual changes in the strength of the direct solar beam which he ascribed to differences in the composition of aerosol in different air masses. Flowers, McCormick and Kurfis (1969) reported measurements of turbidity from a network of stations in the USA equipped with sun photometers. These instruments record the irradiance of the direct beam at a wavelength of 0.55 pm but they

138 citations


Journal ArticleDOI
TL;DR: In this paper, the VUV emission characteristics of Xenon for pressures from 15 to 450 psi were presented, with and without mirrors, and the mean radiative lifetime was 2×10−8.
Abstract: Vacuum ultraviolet (VUV) emission characteristics of xenon for pressures from 15 to 450 psi are presented. Stimulated emission was observed above 200 psi. Experiments were run both with and without mirrors. Without mirrors, the emission was 150 A wide centered at 1700 A, and the mean radiative lifetime was 2×10−8. The energy conversion efficiency was ∼ 20%. With mirrors above 200 psi the emission width narrowed to 17 A centered at 1716 A, and the output was highly directional. The pulse width narrowed from 50 to ∼ 3 nsec.

Journal ArticleDOI
TL;DR: The relaxation method for the inverse solution of the full radiative transfer equation is generalized to solve for all atmospheric parameters which appear in the integrand as functions or functionals, without any a priori information related to the expected solution.
Abstract: The relaxation method for the inverse solution of the full radiative transfer equation is generalized to solve for all atmospheric parameters which appear in the integrand as functions or functionals, without any a priori information related to the expected solution. The method is illustrated by examples in the earth's atmosphere for the determination of water vapor mixing ratio profiles from observations in the 6.3-micron band.

Journal ArticleDOI
TL;DR: In this article, an x-ray band which cannot be identified as a characteristic atomic x ray either of the target atoms or of the projectiles was observed when 70-600-keV argon ions impinge on C, Al, Si, and Fe targets.
Abstract: We report the observation of an x-ray band which cannot be identified as a characteristic atomic x ray either of the target atoms or of the projectiles. The new x ray has been observed when 70-600-keV argon ions impinge on C, Al, Si, and Fe targets. We attribute this x ray to a radiative filling of a vacancy in the $2p\ensuremath{\pi}$ orbital of the Ar-Ar system during the collision.

Journal ArticleDOI
TL;DR: In this paper, the effect of an increase of particles in the atmosphere on the global albedo and accordingly on the thermal regime of the earth is studied by solving the equation of radiative transfer in model turbid atmospheres.
Abstract: The effect of an increase of particles in the atmosphere on the global albedo and accordingly on the thermal regime of the earth is studied by solving the equation of radiative transfer in model turbid atmospheres. Realistic model atmospheres with respect to size and vertical distributions of aerosol as well as reflectivity of the earth surface are assumed, and reflectivity at the top of the atmosphere, transniissivity at the earth surface, and absorptivity of turbid atmospheres are calculated as a function of atmospheric turbidity and the complex refractive index of the aerosol. It is shown that the thermal effect of increasing atmospheric turbidity is greatly affected by the imaginary part of the refractive index. Thus, if it takes a small value as is believed so at present, the earth-atmosphere system cools ofF with increase of turbidity, while if its value is large (ni0.05, ni being the imaginary part of the complex refractive index), heating of the earth- atmosphere system is expected due to...


Book ChapterDOI
01 Jan 1972
TL;DR: A number of recent numerical studies have investigated the effect of radiative processes on the general circulation of the atmosphere and the ocean as mentioned in this paper, where the computed mean distribution of the radiation fluxes is usually specified.
Abstract: The earth as a planet receives virtually all of its energy from solar radiation. The incoming solar radiation at the top of the atmosphere is approximately 2.00 calories per minute through a 1-cm2 surface perpendicular to the solar beam when the earth is at mean distance from the sun (Johnson, 1954).4 The heating of the earth, however, is not uniform, primarily due to its spherical shape. Geographic variation of the earth’s albedo and the nonuniform absorptivity of the earth’s surface produce further modifications to the heating distribution. This horizontal differential heating is a potential source of energy to drive the circulation of the atmosphere and the ocean which transports heat from equatorial to polar regions and eventually adjusts the earth-atmosphere system toward an energy balance between the heating by insolation and the cooling by emission of terrestrial radiation. The manner in which radiative processes interact with the general circulation of the atmosphere has been investigated in a number of recent numerical studies (see, for instance, Manabe et al., 1965; Mintz, 1968; Manabe, 1969; Sellers, 1969; Washington and Kasahara, 1970; Kasahara and Washington, 1971) where the computed mean distribution of the radiation fluxes is usually specified. Most of these studies are based on radiation calculations developed from Northern Hemisphere climatology, although some applications to the Southern Hemisphere make use of the results of Gabites (1950).


Journal ArticleDOI
TL;DR: The tropical stratosphere is heated by radiation due principally to thermal and solar heating by ozone as mentioned in this paper, which extends into the stratosphere mid-latitudes but higher latitudes exhibit cooling due primarily to thermal cooling by CO2 with the warmer hemisphere showing more cooling.
Abstract: Monthly zonal mean global radiative heating rates have been obtained from the surface to 10 mb for all twelve months. Seasonal profiles of the contribution by each constituent are presented in addition to seasonal profiles of net thermal cooling and total radiative heating. Radiation cools the troposphere almost everywhere primarily due to thermal cooling by water vapor with the cooling a maximum in the tropics. The tropical stratosphere is heated by radiation due principally to thermal and solar heating by ozone. This total radiative heating extends into the stratosphere mid-latitudes but higher latitudes exhibit cooling due primarily to thermal cooling by CO2 with the warmer hemisphere showing more cooling. Comparison with previous theory in the Northern Hemisphere shows qualitative agreement although the present study has more resolution because of the better specification of the radiative parameters, in particular, ozone and temperature.

Journal ArticleDOI
TL;DR: In this article, the global mean sources and sinks of radiative energy are calculated for the upper atmosphere of Venus, where the equilibrium temperature is largely controlled through infrared absorption and emission by vibrational-rotational bands of CO2.
Abstract: Global mean sources and sinks of radiative energy are calculated for the upper atmosphere of Venus. We especially consider the region between 90 and 130 km, where the equilibrium temperature is largely controlled through infrared absorption and emission by vibrational-rotational bands of CO2. Source functions for bands deviating from thermodynamic equilibrium are determined as part of the calculation. Radiative transfer in the region of non-overlapping lines is calculated by summing the contribution of individual Voigt lines. Many isotopic and hot bands contribute amounts to 15μ cooling or near-infrared heating at some levels comparable to the contributions by strong bands. The emission of the fundamental 15μ state of C120216 is maintained at near local thermodynamic equilibrium values by the radiation field to pressures three orders of magnitude less than would be expected in considering only relative values of radiative and vibrational relaxation rates. Conversion of near-infrared solar photon ...

Journal ArticleDOI
TL;DR: In this article, the probability of a radiative transition in a magnetic field with spin flip was investigated, including the case of a non-uniform magnetic field, and means of suppressing these effects and also of intentional depolarization of a beam were pointed out.
Abstract: Polarization of electrons arising as the result of radiation during extended motion in a magnetic field is considered. A calculation is made with the quasiclassical operator method of the probability of a radiative transition in a magnetic field with spin flip, including the case of a nonuniform magnetic field. The kinetic equation is obtained for polarization of electrons in an external field with inclusion of radiation effects, and this is used to analyze the kinetics of radiative polarization. Effects are discussed which lead to depolarization of an electron beam in motion in a nonuniform magnetic field, and means of suppressing these effects and also of intentional depolarization of a beam are pointed out. Means are discussed for measurement of the transverse polarization of high energy electrons, and a description is given of an experiment in which the first indication of the existence of the radiative polarization effect has been obtained.

Journal ArticleDOI
TL;DR: In this article, the upward and downward flux at various levels in the atmosphere and ocean is calculated by a Monte Carlo method which includes all orders of multiple scattering, including Rayleigh scattering by the molecules and Mie scattering by aerosols as well as molecular and aerosol absorption.
Abstract: The upward and downward flux at various levels in the atmosphere and ocean is calculated by a Monte Carlo method which includes all orders of multiple scattering. A realistic model of the atmosphere-ocean system is used. In the atmosphere, both Rayleigh scattering by the molecules and Mie scattering by the aerosols as well as molecular and aerosol absorption are included in the model. Similarly, in the ocean, both Rayleigh scattering by the water molecules and Mie scattering by the hydrosols as well as absorption by the water molecules and hydrosols are considered. Separate single-scattering functions are calculated from the Mie theory for the aerosols and the hydrosols with an appropriate and different size distribution in each case. The scattering angles are determined from the appropriate scattering function including the strong forward-scattering peak when there is aerosol or hydrosol scattering. Both the reflected and refracted rays, as well as the rays that undergo total internal reflection...

Journal ArticleDOI
TL;DR: In this paper, the spontaneous radiative dissociations of the discrete vibrational levels of the B 1 Σ + u electronic states of H 2, HD and D 2 of the C 1 Π u electronic state of H2 into the vibrational continuum of the ground X 1 ǫ + g state are calculated as a function of the emission wavelength.
Abstract: The spontaneous radiative dissociations of the discrete vibrational levels of the B 1 Σ + u electronic states of H 2 , HD and D 2 of the C 1 Π u electronic state of H 2 into the vibrational continuum of the ground X 1 Σ + g state are calculated as a function of the emission wavelength. The fluorescent spectra of HD in the Lyman system and of H 2 in the Werner system resulting from an excitation source uniform in wavelength are predicted. The vibrational radiative lifetimes are tabulated as are the fractions of radiative decays that lead to dissociation. The effects of centrifugal distortion are discussed briefly. An appendix describes a sum rule used to check the numerical accuracy of the calculations.

01 Jan 1972
TL;DR: In this paper, the thermal history of the lunar interior has been investigated for many sets of parameters and initial conditions by the construction of mathematical models and these models have been extended to include the effects of melting and redistribution of radioactive heat sources with time.
Abstract: The thermal history of the lunar interior has been investigated for many sets of parameters and initial conditions by the construction of mathematical models. These models have been extended to include the effects of melting and redistribution of radioactive heat sources with time. The models considered include the possibility of heat transfer by lattice conduction, radiative transfer, removal of radioactive heat sources and, in a molten zone, fluid convection. The energy sources are divided into initial temperature sources that operate during the formation of the moon or shortly thereafter, and long-lived radioactive heat sources.

01 Jan 1972
TL;DR: The TPRC Data Series published in 13 volumes plus a Master Index volume constitutes a permanent and valuable contribution to science and technology as discussed by the authors. But it is not suitable for the general public.
Abstract: Abstract : The TPRC Data Series published in 13 volumes plus a Master Index volume constitutes a permanent and valuable contribution to science and technology. This 17,000 page Data Series should form a necessary acquisition to all scientific and technological libraries and laboratories. These volumes contain an enormous amount of data and information for thermophysical properties on more than 5,000 different materials of interest to researchers in government laboratories and the defense industrial establishment. Volume 8 in this 14 volume TPRC Data Series covers seven nonmetallic elements (including 18 varieties of graphite), 46 simple oxides, six groups of mixtures of simple oxides, 59 complex oxides and salts, 185 nonmetallic compounds, 19 groups of intermetallic compounds, 13 groups of cermets, nine groups of pressed nonmetal- metal powder mixtures, 14 groups of miscellaneous mixtures, 14 kinds of glasses, nine kinds of minerals and rocks, and 10 groups of polymers. Data for some of the materials have been critically evaluated and analyzed data graphs are presented in addition to the original experimental data.



Journal ArticleDOI
TL;DR: In this paper, the importance of potential barriers in thermal atomic collision processes is assessed, and numerical results for CH formation suggest that the presence of a potential barrier might enhance the association rate.
Abstract: Potential barriers in atomic interactions often lead to shape resonances in which atoms are held together by the barrier. The importance of these resonances in thermal atomic collision processes is assessed. Radiative association is discussed as an example, and numerical results for CH formation suggest that the presence of a potential barrier might enhance the association rate.

Book ChapterDOI
TL;DR: In this article, the incorporation of spectroscopic information into the radiative transfer equations and a reasonable means of treating radiative energy transfer within gases is presented, where specific restriction is made to infrared gaseous radiation that results from molecular transitions involving both vibrational and rotational energies.
Abstract: Publisher Summary This chapter illustrates the incorporation of spectroscopic information into the radiative transfer equations and presents a reasonable means of treating radiative energy transfer within gases. Specific restriction is made to infrared gaseous radiation that results from molecular transitions involving both vibrational and rotational energies, and emphasis is placed upon the application of the molecular band models to radiative transfer analyses. The chapter also reviews the infrared band spectra, introduces simple band models, and discusses the formulation of total band absorptance information with the aid of these models. The basic equations describing the radiative transfer within an infrared absorbing–emitting gas are formulated and these allow for the radiatively induced departures from local thermodynamic equilibrium. The chapter also presents some illustrative radiative transfer analyses, with emphasis upon physical interpretations and the relative importance of thermal radiation versus molecular conduction as energy transport mechanisms.

Journal ArticleDOI
TL;DR: In this paper, the doubly excited quartet levels in Be II and the displaced term system of Be I were investigated and a term scheme for these quartets was proposed, and a number of the observed lines were also identified with the Be I 2pnl1L, 3L system.
Abstract: An investigation of the doubly-excited quartet levels in Be II and the displaced term system of Be I is described. Beam-foil spectra of beryllium (500-1 600 A, 2 000-6 000 A) showed several transitions which were assigned to doubly-excited Be II. A term scheme for these quartet levels is proposed. A number of the observed lines were also identified with the Be I 2pnl1L, 3L system. Radiative lifetimes have been determined for several excited levels in Be I and Be II.

Journal ArticleDOI
TL;DR: In this paper, the T matrix formalism of scattering theory was applied to derive general expressions for the absorption cross sections, the cross sections for resonance fluorescence and the emission quantum yields from large molecules in the statistical limit.
Abstract: In this paper we apply the T matrix formalism of scattering theory to derive general expressions for the absorption cross sections, the cross sections for resonance fluorescence and the emission quantum yields from large molecules in the statistical limit. In the simple case of an isolated molecular resonance both the absorption line shape and the photon scattering cross section exhibit a Lorentzian distribution on the photon energy, the emission quantum yields are distributed among the ground state vibronic levels according to their radiative widths and, most important, the emission quantum yields are independent of the photon energy and of the spectral width of the exciting light. We were able to derive general expressions for the resonance scattering from a pair of overlapping resonances, including radiative corrections to infinite order. The absorption cross section does not vanish in the region of destructive interference but assumes a finite value which depends on the radiative widths. A sharp maxim...