Vol 55, No 3 (2019)

This paper investigates the stability of a jet flow with a piecewise linear velocity profile in a rotating stratified atmosphere. The linearized set of perturbation equations is reduced to one longitudinal-velocity amplitude equation with turning points. An asymptotic solution of the equation, valid at small Rossby numbers, is derived in terms of the Airy functions. A flow that is stable in a quasi-geostrophic approximation is shown to become unstable due to the emission of inertia–gravity waves. An analytic expression for the growth increment of the perturbations is derived.

The influence of different factors on the total ozone content (TOC) and erythemal UV radiation (Qery) in the atmosphere over northern Eurasia from 1979 to 2059 has been analyzed using a chemistry-climate model developed at the Institute of Numerical Mathematics (INM, Russian Academy of Sciences) and the Russian State Hydrometeorological University (RSHU). The sensitivity of modeled ozone contents to different input data on sea-surface temperature (SST) has been estimated. The TOC trends may significantly differ depending on the SSTs used. The results of the model experiment, which takes into account variations in the anthropogenic emissions of halogen-containing substances, suggest a nonlinear Qery decrease due to the recovery of the ozone layer in the 21st century. The values of Qery for 2016–2020 are 2–5% higher than its values for 1979–1983, on average, for all of northern Eurasia (with its maximum on the order of 6% in the polar latitudes). The Qery values equalize in 2035–2039 and then gradually decrease (when compared to those for 1979–1983) by 4–6% for Asia and 6–8% for northern Europe in 2055–2059. Therefore, variations are observed in the spatial distribution of UV resources, which are most significant in spring and summer: these variations are manifested in the extension of UV-deficiency zones in the north and the reduction of UV-excess zones in the south.

Convection induced by double (differential) diffusion in a rotating medium can generally lead to the transfer of vorticity and, in particular, to its concentration. In geophysical applications, this situation is not usually considered because the spatial and temporal scales of such convection and of rotation effects differ significantly: the period of planetary rotation is many orders of magnitude greater than the characteristic lifetime of the corresponding convective structures in seawater. Attention is given to the fact that there can be some processes in the atmosphere in which a noticeable vorticity transfer caused by a difference in the effective exchange coefficients for various substances seems to be more real. The effects of a double-diffusion-type in the air are in principle possible because of a difference in the rates of transfer of heat, water vapor, and/or heavy admixture. The simplest linear model of convection driven by double diffusion in a rotating medium is considered here. The possibility of a contribution of such effects to the concentration of vorticity during tornado formation is discussed.

According to monitoring data, it is found that the main source of sulfates in carbonaceous particles in the atmosphere of Irkutsk is sulfur dioxide captured from the air. Their accumulation in the particles is caused by heterogeneous chemical reactions (HCRs) and is accompanied by the substitution of hydrocarbonates (\({\text{HCO}}_{3}^{ - }\)) for sulfate anions. In this case, sulfur dioxide is oxidized by ozone in the dry atmosphere, and hydrogen peroxide (H₂O₂), along with dissolved ozone, also participates in the oxidation process in the moist atmosphere. The details of the mechanisms for these HСRs are discussed and the estimates of the dynamics of sulphate production in carbonaceous particles are indicated.

In this paper we study the evolution of the matter distribution pattern of ink droplets falling freely into calm water and forming a cumulative back jet by tracing with high-speed video recording. In the phase of primary contact and immersion, the matter of a drop merging with the receiving liquid is distributed in the form of fine fibers forming a regular striped pattern on the surface of the growing crown and a net pattern consisting of three-, four-, and pentagonal cells at the cavity bottom. The fibrous distributions of the colored liquid remain at all subsequent stages of the flow evolution until the formation of a vortex cascade. Then the picture is blurred due to molecular diffusion in a practically quiescent liquid. The formation of a discrete (fibrous) pattern of the drop matter distribution is associated with the compactness of the region of release of the available potential surface energy during the confluence of liquids that initiates a fast movement of a thin layer. Subsequent fiber preservation is provided by the slowness of molecular diffusion.