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.
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.
The results of calculating the mass absorption coefficient are presented for deeply supercooled water aerosol of cloud formations at the frequencies 100…300 GHz. The computations were made for the supercooling temperatures of 0…–50 °C. New data were used on the values of the real and imaginary parts of dielectric permittivity, based on measurements of the relaxation frequencies in the centimeter band. The model computations were compared to the results obtained previously by other authors. The results proved to be essentially different for deeply supercooled water at the temperature below –20…–30 °C. A conclusion is made that the formulae used for the real and imaginary parts of dielectric permittivity of water are relevant for the frequencies 200…300 GHz.
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 measurements of an imaginary part of relative dielectric constant of supercooled water in the temperature range from
–20 to –120°C at the frequencies of 7-11 GHz were made. We used water captured in silicate pores in order to reach
deep supercooling. We determined an increased value of dielectric losses in the temperature range from –30 to –70°C
with extremums near –45°C and –70°C as compared with a known model. These peculiarities are related to the influence
of the second critical point and phase transition of water into ice.
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