The bows and rings of dawn and dusk

The arcs of dawn and dusk are natural phenomena that define the boundary of the border between day and night. They are associated with the refraction of solar rays at high angles of incidence that converge to project an arc of light onto the back side of the earth's atmosphere. The rings of dawn and dusk, in turn, are associated with rays, also at large angles of incidence, which converge to project the image of the Sun. Arcs and rings become visible by scattering light by clouds or particles suspended in atmospheric air in the region in which they occur. Here we show a model that describes these natural phenomena and report the first-time record image produced in July of this year.

Ice 0: the experimental proof of its existence – the result of combining approaches used in radiophysics, geology and geography

The experience of combining the efforts of researchers working at the interface of radiophysics, geology and geography is discussed. The effectiveness of such collaboration of researchers is shown by the example of the experimental proof of the existemce of a new crystalline modiciation of ice, ice 0. This kind of ice is formed at the temperature below –23 °C out of supercooled water, and, together with ice Ih and ice Ic, may be formed at the temperatures and pressures corresponding to the surface layers of the Earth’s atmosphere. For this reason, this study is of great interest for understanding the natural processes taking place in the geospheres (atmosphere, cryosphere, biosphere, and hydrosphere).

A revised lower estimate of ozone columns during Earth’s oxygenated history

The history of molecular oxygen (O 2 ) in Earth’s atmosphere is still debated; however, geological evidence supports at least two major episodes where O 2 increased by an order of magnitude or more: the Great Oxidation Event (GOE) and the Neoproterozoic Oxidation Event. O 2 concentrations have likely fluctuated (between 10 −3 and 1.5 times the present atmospheric level) since the GOE ∼2.4 Gyr ago, resulting in a time-varying ozone (O 3 ) layer. Using a three-dimensional chemistry-climate model, we simulate changes in O 3 in Earth’s atmosphere since the GOE and consider the implications for surface habitability, and glaciation during the Mesoproterozoic. We find lower O 3 columns (reduced by up to 4.68 times for a given O 2 level) compared to previous work; hence, higher fluxes of biologically harmful UV radiation would have reached the surface. Reduced O 3 leads to enhanced tropospheric production of the hydroxyl radical (OH) which then substantially reduces the lifetime of methane (CH 4 ). We show that a CH 4 supported greenhouse effect during the Mesoproterozoic is highly unlikely. The reduced O 3 columns we simulate have important implications for astrobiological and terrestrial habitability, demonstrating the relevance of three-dimensional chemistry-climate simulations when assessing paleoclimates and the habitability of faraway worlds.

Earth’s Stratospheric Aerosol Parameters Reconstruction from Polarimetric Measurements of the Sky

Earth’s climate changes are the result of natural changes in the energy balance of Sun irradiation and influence of anthropogenic factors on the variations of ozone layer thickness and stratospheric aerosol abundance. It is developed a miniature polarimeter for satellite polarimetric experiments in the ultraviolet region of the sunlight spectrum. The main task of this device is to the obtain an information on the stratospheric aerosol physical properties. We tested this polarimeter on a bench specially designed and manufactured as well. It is possible to measure by it the phase dependences of the degree of linear polarization (DLP) of solar radiation scattered by the Earth’s atmosphere. A set of special computer programs was developed for comparing the spectral polarimetric measurements DLP data of cloudless sky with model calculations of DLP for the artificial gas-aerosol medium. Thus, the prototype of satellite polarimeter as well as special computer programs make it possible to study the Earth’s atmosphere aerosol physical characteristics.

Modeling of the Dark Phase of Flight and the Impact Area for Meteorites of Real Shapes

Aims. The complex dynamics of bodies, originating from the interplanetary matter and passing through Earth’s atmosphere, defines their further position, velocity, and final location on Earth’s surface in the form of meteorites. One of the important factors that affect the movement of a body in the atmosphere is its shape and orientation. Our goal is to model the interaction of real shape meteoroids with Earth’s atmosphere and compare the results with the standard spherical body approach. Methods. In the simulation, we use 3D models of fragments of the Košice meteorite with different sizes and shapes. Using a 3D model of fragments, we consider the real shape of the body to define its resistance properties during atmospheric transition more specifically. The simulation is performed using virtual wind tunnel in the MicroCFD (Computational Fluid Dynamics) software to obtain more realistic drag coefficients and using the µ(m)-Trajectory software to model the particle trajectory in the atmosphere including the wind profile. The final outputs from these programs are the drag coefficient as a function of the altitude and the particle orientation. Using these parameters we get the more realistic body trajectory and the impact area coordinates. Comparison of the results for real and spherical model meteorite impact location is discussed. Results. Simulation showed significant differences in trajectory and the impact area for the different real body orientations compared to the spherically symmetric body. Also, an important result is a difference in the impact area of the real body with a specific orientation without rotation and the body with considered rotation. The significant difference between the modeled impact of a real shape body and its real place of finding compared to a spherically symmetric body indicates the importance of the method used.

A Survey of Structure of Atmospheric Turbulence in Atmosphere and Related Turbulent Effects

The Earth’s atmosphere is the living environment in which we live and cannot escape. Atmospheric turbulence is a typical random inhomogeneous medium, which causes random fluctuations of both the amplitude and phase of optical wave propagating through it. Currently, it is widely accepted that there exists two kinds of turbulence in the aerosphere: one is Kolmogorov turbulence, and the other is non-Kolmogorov turbulence, which have been confirmed by both increasing experimental evidence and theoretical investigations. The results of atmospheric measurements have shown that the structure of atmospheric turbulence in the Earth’s atmosphere is composed of Kolmogorov turbulence at lower levels and non-Kolmogorov turbulence at higher levels. Since the time of Newton, people began to study optical wave propagation in atmospheric turbulence. In the early stage, optical wave propagation in Kolmogorov atmospheric turbulence was mainly studied and then optical wave propagation in non-Kolmogorov atmospheric turbulence was also studied. After more than half a century of efforts, the study of optical wave propagation in atmospheric turbulence has made great progress, and the theoretical results are also used to guide practical applications. On this basis, we summarize the development status and latest progress of propagation theory in atmospheric turbulence, mainly including propagation theory in conventional Kolmogorov turbulence and one in non-Kolmogorov atmospheric turbulence. In addition, the combined influence of Kolmogorov and non-Kolmogorov turbulence in Earth’s atmosphere on optical wave propagation is also summarized. This timely summary is very necessary and is of great significance for various applications and development in the aerospace field, where the Earth’s atmosphere is one part of many links.

Analysis of the trajectory of spacecraft return from the lunar surface to a given region of the Earth

The paper describes a method developed for designing the trajectory of a spacecraft flight from the lunar surface to a given area of the Earth’s surface and analyzes a single-pulse flight scheme, in which the trajectory of a take-off lunar rocket is approximated by a single velocity pulse. The characteristics of the spacecraft entry into the Earth’s atmosphere are chosen so as to ensure that the conditions along the entry corridor during the ballistic entry are met and to ensure the landing of the reentry vehicle at a given point on the Earth’s surface. The criterion for optimizing the trajectory of the spacecraft return to the Earth is considered to be the value of the impulse that provides the spacecraft launch from the lunar surface. The method relies on the analysis of an auxiliary problem, the solution of which makes it possible to estimate the main properties of the investigated maneuver and find an initial approximation for the selected characteristics of the optimized trajectory.