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/m<sup>3</sup> 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.