M. V. Kabanov

Monitoring environmental electromagnetic fields. 1. Remote-sensing methods

This paper discusses monitoring electromagnetic fields (natural and artificial) in the atmosphere. Methods are described for remote sensing of the atmosphere and surface in order to examine static and alternating electromagnetic-energy fluxes in the biosphere.

Angular intensity distribution of scattered light in systems of closely spaced particles

The results of experimental and computational investigations of the dependence of the angular intensity distribution of scattered light on the concentration of scatterers are discussed. It is shown that a high density of small and large scatterers in a three-dimensional system results in a deformation of the scattering indicatrix. The changes in the angular distribution of intensity of the scattered light at large concentrations are explained by the appearance of fields of multiply scattered waves at significantly lower optical thicknesses than for independent scatterers.

Low-frequency intensity fluctuations of radiation from a distant source in the infrared region of the spectrum. II

The results are considered of signal-fluctuation measurements of a thermal source in the infrared region of the spectrum on an extended surface path. Experimental averaging functions are obtained for receiver-transmitting apertures in the case of large limits of variation of the latter. The dependence of the dispersion of the fluctuations on the wavelength of the radiation is investigated over the range 1.06 to 3.9 μ.

Statistical screening of a light beam and fluctuations in the transparency of dispersed media

Results of mathematical statistics about the covering of a plane by circles are used for a quantitative description of transparency fluctuations. It is shown from a comparison of the theoretical and experimental results for the dispersion of fluctuations of passing radiation that statistical screening is the governing reason for the fluctuations of passing radiation in dispersed media. An empirical formula permitting the approximate computation of the dispersion with an accuracy sufficient for practical purposes is proposed for large optical depths.

Effect of the relative humidity on the attenuation of optical radiation by aerosols in the atmosphere

On the basis of a study concerning the optical transparency of atmospheric mists, an analysis is made of the relation between the attenuation by aerosols and the relative air humidity under autumn conditions (radiation wavelengths within the 0.56–12.0 Μ range). It is shown that the attenuation coefficient changes nonmonotonically as the humidity increases from 40 to 100%. Hypothetical mechanisms of interaction between aerosol particles and water vapor are suggested which would explain this trend.

Fluctuation characteristics of singly scattered light intensity

The correlation function and variance of the intensity fluctuations of singly scattered light are computed for a system of independent scatterers subjected to Brownian motion and illuminated by a light beam. The computation is carried out taking account of space and time averaging by the detector. The results obtained agree with available test data.

Dependence of the optical transmission function of a turbulent atmosphere on the averaging time

Measurements of the optical transmission function (OTF) of the atmosphere of an inclined path 3.5 km long, based on a photographic method, are described, and the effect of meteorological conditions and averaging time (0.017–30 sec) on the resultant values is considered. The experiments indicate that, for any fixed frequency, there are regions in which the OTF of the atmosphere varies sharply with exposure. The general form of this variation is consistent with theory.

Apparatus and method for measuring the spectral transmittance of the atmosphere in the 0.48–12μ band with medium resolution

Apparatus for measuring the spectral transmittance of the atmosphere in the visible and infrared parts of the spectrum over long paths close to the surface of the earth is described. A method of measurement is described which considerably simplifies the processing of the experimental data.

Low-frequency fluctuations of the intensity of distant sources in the infrared. I

An apparatus for measuring the intensity fluctuations of a distant source and the spectral transmittance of the atmosphere in the infrared is described. The apparatus is composed of a horizontal telescope, an infrared monochromator, and a recorder.The authors discuss the results of preliminary measurements of the intensity fluctuation probability distribution at large receiving apertures and the dependence of the fluctuations on the wavelength of the radiation.