The passage of electromagnetic radiation in the visible range through a plate of Ih ice with a condensed film of ice 0 on it was studied. Ice 0 is a recently discovered transitional form of crystalline ice from supercooled water at temperatures below –23 °C to Ih or Ic ice. The existence of significant attenuation of radiation in the temperature range from –80 to – 23 °C has been established. The effect is associated with the appearance of a layer with high electrical conductivity at the boundary between Ih ice (dielectric) and ice 0 (ferroelectric). Attenuation is determined by scattering and absorption of electromagnetic radiation propagating through the sample due to plasmon resonance in nanometer-sized films.
The work presents the results of long radiometric measurements of the atmosphere in the city of Chita during the winter period at a frequency of 34 GHz. The power of thermal radiation was also recorded in the thermal infrared range (7…14 μm). Simultaneously with the readings of the brightness and radiation temperature, meteorological parameters of the atmospheric ground level layer and illumination were recorded. As a result, an increase in the value of the radiation temperature in the IR range by 20 K and up to 1 K at a frequency of 34 GHz was detected during the freezing of fog at an ambient air temperature in the surface layer of -25 °C. In addition, variations in atmospheric thermal radiation were detected during cloudiness and pollution with soot aerosol particles
A method of active microwave measurements of near-surface aerosol is proposed, aimed at discovering formation of ice 0 in it. This ice is formed, when water temperature proves to be below –23 °C. Its deep supercooling may occur in media having pores of nanometric sizes, for example, in aerosol particles. As ice 0 contacts dielectric, a double electric layer emerges, having high electric conductivity, exceeding the electric conductivity of the contacting media by many orders of magnitude. As a result, the effects of scattering of electromagnetic radiation increase sharply on accumulations of particles, and it becomes possible to detect such formations in different bands, including the IR-band. The proposed method of detecting scattered electromagnetic radiation in cold aerosol caused by formation of ice 0 in it has started.
In this study, field measurements of the thermal radiation of freshwater ice cover in the area of ice hummocks are presented. The studies were made at the wavelengths 8.8 mm and 2.3 cm and in the infrared band at the wavelengths 8– 14 μm. It has been demonstrated that the thermal radiation of ice hummocks compared with the background radiation of ice has primarily increased radiation power in the centimeter band but decreased values in the millimeter and IR-bands. In the IR-band, the satellite images (Landsat-8) show the same effect. Decrease of radio brightness in the millimeter band is related to the effect of radiation scattering on the inhomogeneities of the structure. In the IR-band, the effect may be determined by evaporation of snow from the surface of an ice hummock. This study will be of interest for the specialists investigating sea ice, on which ice hummocks are also formed.
Polluted winter atmosphere was measured at air temperature inversion above the city of Chita in the thermal IR band. A rise in the radiation temperature at the thermodynamic temperature of the air layer –23 °C was registered near the site on which the measurement equipment was installed. The effect is supposed to be associated with formation of ferroelectric ice 0 in wetted porous dielectric particles and with the rise of electromagnetic losses at the temperatures below the indicated value.
A method of measuring reflected radiothermal radiation of the Sun and the Earth from mesospheric clouds is proposed. To substantiate the method, an experiment was performed for measuring laser radiation at the wavelength of 0.52 μm through dielectric plate, with ice 0 sedimented from the gas fraction. In this experiment, intense absorption of probing radiation was discovered at the temperatures from –80 to –23 °C. In a field experiment, a simultaneous rise of radio brightness temperature at ~5 К was recorded at 4 wavelengths of the microwave band.
Formation of ice particles of noctilucent clouds is discussed. These ice particles are supposed to contain ice 0, the recently discovered ferroelectric modification of ice. At the contact of ice 0 with the surface of a dust particle, there emerges a thin layer having high electric conductivity, which accounts for intensive scattering of electromagnetic radiation in the broad band of frequencies. Another mechanism is suggested for emergence of water in the mesosphere due to reaction of interaction between hydroxyl molecular groups on the surface of a silicate particle and molecules of gaseous hydrogen. It is proposed to make observations over noctilucent clouds by employing the methods of microwave radiometry.
The results of laboratory measurements of the attenuation coefficient of supercooled water, without scattering, at the frequencies from 140 to 180 GHz and in the temperature range from 0 to -45 °C are presented. The obtained values of the attenuation coefficient have been used to evaluate linear attenuation coefficient both in atmospheric water aerosols and in aerosols consisting of wet solid particles. In the examined range of frequencies, linear attenuation for the liquid water content of 0.1 g/m3 at the temperatures of -40…-45 °C is 1.2…1.5 dB/km.
The paper presents experimental data on electromagnetic radiation propagation at a frequency of 5.2 GHz through pine needles at negative temperatures. Hysteresis of electromagnetic losses under a temperature cycling in the range from -10 to -30°С is revealed. Variations in the signal power at the same temperature and mean attenuation of 3 dB reach 1.6 dB. This effect should be taken into account under remote sensing of coniferous forests in winter.
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