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The cavitation and cavitation-ablation mechanisms of formation of mineral nano-and microspherules in hydrothermal fluids are considered. The formation conditions of nano-and microspherules were studied with regard to the depth of host rock occurrence on the basis of the theory describing the cavitation mechanism. It is shown that the temperature and pressure of hydrothermal fluid as functions of the depth of host rock occurrence may markedly affect the dimensions of cavitation bubbles, the temperature within them at the moment of greatest compression, and the time of bubble collapse in the fluid. the dimensions of nano-and microspherules produced by cavitation depend only slightly on the depth of host rock occurrence and are mainly controlled by the thermophysical properties of their constituents. Characteristic dimensions of nanospherules formed as a result of ablation from the surface of overheated material have been obtained. 相似文献
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The results of studying the finely dispersed particles in the natural and anthropogenic geosystems are briefly reviewed. The analysis is confined to the solid Earth, the troposphere, and the stratosphere. Definitions are given for the main fine-dispersed objects in geophysics (nanocrystals, nano- and microscale particles, nanoclusters, nanoporous materials, colloidal particles, aerosols, etc.). The specific mechanical properties of nanoobjects are outlined, and the limiting particle sizes at which these particularities are significant are estimated. The studies of fine-dispersed particles formed in the experiments on destruction of rocks are described. The role of fine particles in the Atmospheric Brown Clouds is discussed, and the effect of these clouds on the climatic changes is analyzed. Participation of fine particles in the interactions between the geospheres is considered by the examples of extraterrestrial dust, eruption of the Eyjafjallajökull volcano, and vortex entrainment of the fine particles from the troposphere into the stratosphere. 相似文献
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Adushkin V. V. Nifadiev V. I. Chen B. B. Popel S. I. Kogai G. A. Dubinskii A. Yu. Weidler P. G. 《Doklady Earth Sciences》2020,493(2):632-635
Doklady Earth Sciences - On the basis of the data on perturbations in the Earth’s atmosphere recorded before and after 52 significant earthquakes that occurred during the period from 1997 to... 相似文献
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I.?A.?KuznetsovEmail author A.?V.?Zakharov G.?G.?Dolnikov A.?N.?Lyash V.?V.?Afonin S.?I.?Popel I.?A.?Shashkova N.?D.?Borisov 《Solar System Research》2017,51(7):611-622
Physical conditions in the near-surface layer of the Moon are overviewed. This medium is formed in the course of the permanent micrometeoroid bombardment of the lunar regolith and due to the exposure of the regolith to solar radiation and high-energy charged particles of solar and galactic origin. During a considerable part of a lunar day (more than 20%), the Moon is passing through the Earth’s magnetosphere, where the conditions strongly differ from those in the interplanetary space. The external effects on the lunar regolith form the plasma-dusty medium above the lunar surface, the so-called lunar exosphere, whose characteristic altitude may reach several tens of kilometers. Observations of the near-surface dusty exosphere were carried out with the TV cameras onboard the landers Surveyor 5, 6, and 7 (1967–1968) and with the astrophotometer of Lunokhod-2 (1973). Their results showed that the near-surface layer glows above the sunlit surface of the Moon. This was interpreted as the scattering of solar light by dust particles. Direct detection of particles on the lunar surface was made by the Lunar Ejects and Meteorite (LEAM) instrument deployed by the Apollo 17 astronauts. Recently, the investigations of dust particles were performed by the Lunar Atmosphere and Dust Environment Explorer (LADEE) instrument at an altitude of several tens of kilometers. These observations urged forward the development of theoretical models for the lunar exosphere formation, and these models are being continuously improved. However, to date, many issues related to the dynamics of dust and the near-surface electric fields remain unresolved. Further investigations of the lunar exosphere are planned to be performed onboard the Russian landers Luna-Glob and Luna-Resurs. 相似文献
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The Earth's middle atmosphere at altitudes of 80-95 km exhibits layered phenomena known as noctilucent clouds and polar mesosphere summer echoes. These structures are believed to be associated with the presence of large quantities of charged dust or aerosol particles. The sign of the charge depends on the material composition of the latter as well as the environment. The grains are normally composed of ice together with possible metallic impurities. Particles of pure ice are always charged negatively, but if the metal content is sufficiently high, they can become positive. The characteristics of self-organized structures on the dust acoustic time scale depend strongly on the sign of the charge, and the structures can appear as either electron (ion) density humps or dips. Such a physical distinction can be used for the identification and diagnostics of noctilucent clouds and polar mesosphere summer echoes. 相似文献
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V. V. Adushkin B. B. Chen S. I. Popel P. G. Weidler F. Friedrich Yu. N. Izvekova 《Doklady Earth Sciences》2016,466(2):177-182
The properties and originof small C-bearing and mineral particles are thoroughly studied above the Central Asian Region. It is shown that the Aral Sea soils play a significant role in accumulation of the higher concentrations of the metals of the crustal origin and rare-earth elements in small mineral particles of samples 相似文献
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