A new aspect of condensation theory

This paper examines the effects of the mixing of dry air into a cloud top from the point of view of the droplet spectra. It is shown theoretically that the resulting cycling of the air up and down in the cloud, as seems to be the essential mechanism by which cumuli have been diluted to their observed liquid water mixing ratio, can double the largest drop radius and generate cloud parcels containing drops of all sizes up to this maximum. These changes in the droplet distribution with size occur by a process which is not greatly influenced by the cloud condensation nuclei or the details of droplet growth since maritime like spectra can develop in continental type cumuli. It shows that large numbers of cloud condensation nuclei should not have much effect in inhibiting the rainforming process by reducing coalescence growth. On the contrary, the controlling parameters which determine precipitation efficiency and times seem to be those which control the mixing.     

Large-scale structure of magnetospheric plasma

Recent investigations of magnetospheric plasma structure are summarized under the broad categories of empirical models, transport across boundaries, formation, and dynamics of the plasma sheet. This report reviews work in these areas during the period 1991 to 1993. Fully three-dimensional empirical models and simulations have become important contributors to our understanding of the magnetospheric system. Some new structural concepts have appeared in the literature: the entry boundary and geopause, the plasma sheet region 1 vortices, the low-energy layer, the adiabaticity boundary or wall region, and a region in the tail to which we refer as the injection port. Traditional structural concepts have also been the subject of recent study, notably the plasmapause, the magnetopause, and the plasma sheet. Significant progress has been made in understanding the nature of plasma sheet formation and dynamics, but the acceleration of electrons to high energy remains somewhat mysterious.     

Comparison of short- and long-periodP-wave travel times and arrival angles

Summary Using about 100 earthquakes recorded on both the short-period and long-period matched three-component seismograph systems at Umeå (UME) in northern Sweden, relativeP-wave travel times (LP-SP) are measured and arrival angles (incidence and azimuth) are determined from relative amplitudes ofP. Long-period onsets appear to register consistently later than short-period ones by a couple of tenths of a second. This figure is of the same order as the uncertainty in T _LS (difference between LP and SP onset times), but still is shown to be of some statistical significance. The effect is believed due, at least in part, to the relative inability of the long-period seismometer to visibly register an initial shorter-period lower-amplitude focal phase from some earthquakes.The dip on crustal interfaces implied by the short-period azimuth and incidence-angle anomalies is 7 to 15 times greater than that implied by the long-period anomalies. This effect is believed due to undulation or irregularity of, foremost, the Moho, as well as other crustal boundaries. The wavelength of, say, Moho undulations would seem to be limited above and below by considerations of the dominant long-period wavelengths (100 km) and of the diameter of Moho sampled by the short-period waves (50 km). The possible undesirable effect of the crustal layering on the components of surface motion, and thus on the arrival angles, is discussed and cautiously dismissed, due to the absence of sedimentary layering, in favour of the above interpretation.     

A note on the general concept of wave breaking for Rossby and gravity waves

A recently proposed general definition of wave breaking is further discussed, in order to deal with some points on which misunderstanding appears to have arisen. As with surface and internal gravity waves, the classification of Rossby waves into breaking and not breaking is a generic classification based on dynamical considerations, and not a statement about any unique signature or automatically recognizable shape. Nor is it a statement about passive tracers uncorrelated with potential vorticity on isentropic surfaces. A strong motivation for the definition is that proofs of the nonacceleration theorem of wave, mean-flow interaction theory rely, explicitly or implicitly, on a hypothesis that the waves do not break in the sense envisaged.The general definition refers to the qualitative behaviour of a certain set of material contours, namely those, and only those, which would undulate reversibly, with small slopes, under the influence of the waves' restoring mechanism, in those circumstances for which linearized, nondissipative wave theory is a self-consistent approximation to nonlinear reality. The waves' restoring mechanism depends upon the basic-state vertical potential density gradient in the case of gravity waves, and upon the basic-state isentropic gradient of potential vorticity in the case of Rossby waves. In the usual linearized theory of planetary scale Rossby waves on a zonal shear flow, the relevant material contours lie along latitude circles when undisturbed.     

Numerical modeling of the high-latitude F-layer anomalies

The results of a detailed numerical study of the behaviour of the convective polar ionosphere are presented. The developed theoretical model produces three-dimensional distribution of electron density, electron and ion temperature. The effects of auroral particle precipitation on the density and temperature structures are studied for winter and low solar activity conditions. The high-latitude ionospheric features, such as the tongue of ionization, the main trough the polar ionization peak, the auroral ionization peak, the high-latitude ionization hole, the tongue of electron temperature, the high latitude minima of electron, temperature, and the ion temperature hot spot are obtained from calculations.Numerically obtained results are used for determining the HF propagation paths in the polar ionosphere. The effects of ionospheric irregularities on high frequency ionospheric radio waves are investigated by using a three-dimensional ray-tracing computer program. Ray-path trajectories are presented for different values of the elevation angle of transmission. From our study, it was found that large-scale irregularity structures of the high-latitude ionosphere, in the presence of the earth's magnetic field, significantly affect high frequency radio wave propagation.     

Results of concentration and mobility measurements of positively and negatively charged particles taken by a rocket-borne parachuted aspiration (Gerdien) probe in the height region from 72 to 39 km

Summary With a self-neutralizing, rocket-borne parachute aspiration probe concentration and mobility measurements of positively and negatively charged carriers were made between 72 and 40 km over Sardinia. Between 72 km and 60 km a heavy and a light group of positively charged particles were found. The heavy group was more abundant than the hight group in the greater heights. For the negatively charged particles only one mobility group was found which roughly corresponded to the mobility of the light group of the positively charged carriers. The probe was designed so that no electrons could enter the analyzer section of the aspiration system. By this the electron concentration was given by the difference in concentration between the positively and negatively charged particles.This paper was read byH. Dolezalek, in an abbreviated form supplied by the authors.     

Changes in Magnetic Parameters After Sequential Iron Phase Extraction of Eastern Mediterranean Sapropel S1 Sediments

Iron is distributed over different minerals (i.e. silicates, pyrite, detrital oxides) that are present in a sediment sequence that formed under anoxic conditions. After post-depositional re-oxidation of the sediments pyrite is no longer present and diagenetic iron phases constitute an important portion of the iron in the oxidised part of the sapropel. They are very fine-grained making them amenable to analysis by means of sequential extraction and mineral-magnetic methods. The sequential extraction shows that besides iron in silicates, iron mainly occurs in amorphous oxides in the oxidised part of the S1 sapropel. Pyrite constitutes an important fraction in the still reduced part of the S1 sapropel. Some silicon is dissolved during the extraction for the amorphous oxides, suggesting that amorphous iron also occurs as ferro-silicate coatings. Mineral-magnetic analysis involved component analysis of the isothermal remanent magnetisation (IRM) and hysteresis loop measurements. Three coercivity phases could be identified in the IRM component analysis; these were interpreted as detrital magnetite, hematite, and biogenic magnetite. The diagenetically formed iron phases influence the parameters of the IRM components. Hysteresis measurements together with the IRM component analysis, indicate the importance of bacterial magnetite in the oxidised sapropel, particularly in the lower part of the active oxidation zone.     

Approximative ray tracing and the accuracy of earthquake localization in media approximated by block structures

Summary Localization errors made by approximating a given medium by a homogeneous rectangular block model and due to the approximative solution of two-point ray tracing are estimated for four different structures. The separate influence of the individual characteristics of the medium is discussed. The iterative Geiger method supplemented by a generalized inversion of the damped least-squares and Marquardt algorithm is used for localizating five hypothetical hypocentres using 9 stations. Travel times in the original structures, used as input data for localization, are calculated using a special ray tracing system.

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am uu auauu a annuau a ¶rt; ¶rt; ma u ma ¶rt;¶rt; u annuau m a ¶rt; munau nuuum .

     

Heat flow variations in the presence of an irregular contact of different rock type

Summary The effect of an irregular contact of two different rock types on the surface heat flow was analysed for the Zlatý Kopec region in northwest Bohemia. The 2-D geothermal model of subsurface structures was compiled according to measured values of the thermal conductivity and heat sources and by using isobaths map of the metamorphite-granite boundary. The heat flow was computed numerically from the temperature distribution obtained as a finite-difference solution of the heat conduction equation. It was found that the heat flow variation, corresponding to the most probable model, amounts approximately to the half of the actually observed changes. The surface heat flow is affected strongly by the thermal conductivity contrast between the overlying metamorphites and underlying granites and, on the contrary, it is little sensitive to the heat production difference between both rock types. It seems, therefore, that, despite the big heat production contrast observed, the main source of the heat flow variability are thermal conductivity inhomogeneities.

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¶rt;am uu mama ¶rt; m¶rt; mun n¶rt; a nm mn nm ¶rt; amu am n ana¶rt; uu. a u au mnn¶rt;mu u mnauu u n amu aauauaum — mauu n¶rt; a maa ¶rt;a ¶rt; nunm mm. n nm auma n -am u au mnn¶rt;mu. mam ¶rt;m, m auau mn nma ma a m ¶rt;u, n¶rt;mam nuuum nu a¶rt;a uu. a nm m u um aua mnn¶rt;mu ¶rt; aauu mauuu n¶rt;au u uaauaum, u am, nm a mum auu mnauu ¶rt; muu n¶rt;au. aum, m, m a a¶rt;a au mnauu,a umu auau mn nma m ¶rt;¶rt;mu uma mnn¶rt;mu.

     

Generators in atmospheric electricity

Summary The definition of a generator in atmospheric electricity is considered, and various phenomena are discussed as to whether they can be described as generators.     

The field of shortwave radiation in case of A clear sky

Summary A simple method of calculating fluxes and intensities (both spectral and integral) of radiation in the spectral region 0.29–4 in troposphere and lower stratosphere is proposed. This method allows to calculate with satisfactory accuracy the mean radiative regime of real atmosphere and to solve a wide range of problems both atmosphere-optical and thermal with arbitrary receivers of radiation. ( ) 0.29–4 . , .     

Asymmetry in a nearly symmetric dynamo

mam u¶rt;m uu aumuu a m n uamu ¶rt;u nmu umu ¶rt;ua a maum ¶rt;a amu u. a um naa nu nu naama umuu , au a um aumu m n aau umuu mau aum n. aam, m mum au ¶rt;-amu a ma mu aum u u n a aumu m n.     

On latitudinal variations of temporal characteristics of the VLF chorus in the upper ionosphere

Summary The elements of the VLF chorus, observed simultaneously at a ground station and satellite in polar orbit, can be used to determine the differences in the arrival times of waves and their dependence on latitude. Mostly does not change practically over a wide range of latitudes, however, in some cases it may increase appreciably at low value of L. Model computations of the propagation time, based on the assumption that the source of the chorus is located close to the equatorial plane, have indicated the possibility of explaining the increase in at low latitudes by the presence of a step in the electron density profile close to this plane.

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a¶rt;u m a u a um nmu nun um nm n¶rt;um amu u nu¶rt;a ma a u u um auum (L). um a a m ¶rt;uana um, m a a¶rt;am aum uu a a L-a. am anmau n¶rt;nuu amua umua naam m um uu a uu uma auu mnu an¶rt;uu m mauu amua nmu.

     

Does the interplanetary magnetic field and the solar activity contribute to the tropospheric circulation?

A significant tendency is shown for both Etesians and (+, –) sector boundaries of the interplanetary magnetic field (IMF) to occur on the same solar rotation days, during the main period of the Etesians effect (July–August). In addition, the solar activity seems to control the Etesians distribution within the IMF sector structure. In the epoch of maximum there is a significant tendency of Etesians to occur during toward IMF days. In contrast, in the epoch of minimum Etesians occur mainly during away IMF days. Finally, in the epoch of intermediate the Etesians are uniformly distributed in away and toward IMF days. Since these conclusions are statistically significant at high confidence levels, it is fair to assume that IMF and solar activity seem to contribute, to some extent, to the Etesians occurrences, as well as to their distribution within the solar rotation and the IMF sector structure; that is, some solar contribution to the tropospheric circulation is implied.     

Deuteron whistlers in the outer ionosphere

Summary Upgoing and downgoing deuteron whistlers were found on VLF records made by Interkosmos 5, 14 and 19 satellites even at heights below 1000 km. To account for them, a slight admixture ofD ⁺ ions has been introduced into the ionospheric plasma model with the usual content of only three ion speciesH ⁺,He ⁺ andO ⁺. Relations derived for the calculation of characteristic frequencies in a five-component plasma (e,H ⁺,D ⁺,He ⁺,O ⁺) are given as well as the values of characteristic frequencies calculated on this basis. The observed features of upgoing and downgoing deuteron whistlers could be explained by the calculation results, and it is also possible to formulate some conclusions for the purposes of plasma diagnostics.

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mu um, anmau a ma u u, u a a nmua m 5, 14 u 19 a ma ¶rt;a 1000 . u u a ¶rt;a ¶rt; u na ¶rt;au uH ⁺,He ⁺,O ⁺ aa nuD ⁺ u. m mm ua nma ¶rt;a ¶rt; aamumuu amm ¶rt;a ¶rt;u na. uu aamumuu amm nuu um a¶rt;a mu ¶rt;mu um. a m ¶rt; unam aamumuu ¶rt;mu um ¶rt; u¶rt;au naam na.

     

Numerical study of non-linear storm-surges

Summary The problem of storm-surges is investigated in a rectangular basin, setting up a numerical hydrodynamical model using the shallow-water equations. The forcing exerted by the atmosphere is given in the idealized form of a constant wind blowing over a section of the basin. The case in which the window of wind is moving is considered and for a basin that has the same dimensions of the Adriatic Sea. The conditions that give the maximum surge at one edge of the basin are investigated.

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Riassunto Il problema relativo alle storm-surges viene studiato in un bacino rettangolare, costru endo un modello idrodinamico numerico ed usando le equazioni relative ad acqua poco profonda. Lo stress esercitato dall'atmosfera è dato nella forma idealizzata di un vento costante che soffia sopra una sezione del bacino. Si considera il caso in cui la finestra di vento è in moto e per un bacino che ha le medesime dimensioni del mare Adriatico. Si studiano le condizioni che provocano il massimo dell'innalzamento ad un estremo del bacino.

     

The relation between Gaussian beams and Maslov asymptotic theory

Summary The application of Maslov asymptotic theory in a general 3-D mixed subspace of 6-D complex phase space is proposed to obtain the integral superpositions of Gaussian packets and beams. The ray method and the superposition of plane waves (Maslov method of Chapman and Drummond [7]) are special limiting cases of the above mentioned approach. The same high-frequency asymptotic expansion formulae for seismic body waves were derived previously in [8] using the Gaussian beam method.

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uu aunmmu muu aa m a n¶rt;nmam mu a nmama n¶rt; ¶rt; nu uma nnuu a nam u n. nnuu nu u m¶rt; m nuau n¶rt;u au n¶rt; n¶rt;¶rt;a. a amm aunmmuu u a n m¶rt; a n [8].

     

Regularization of downward heat flow continuation

Summary Some regularization approaches to downward heat flow continuation from the Earth's surface to the depth of interest are presented, provided the heat transfer is described by the homogeneous steady-state equation. The Fourier transform of horizontal coordinates is used and the relation between the regularization of the heat flow spectrum and the regularization of the heat flow in the spatial domain are discussed. The utilization of an a priori information about the subsurface heat flow is mentioned.

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¶rt; m zuau n¶rt;¶rt; n¶rt;u u nmz mnz nma n¶rt;nuu, m n mna nuam ¶rt;¶rt; maua au (au anaa). na naau zuma ¶rt;uam u ama ¶rt; zuau mnz nma u uau z nma. nma m nuu anu u n¶rt;nmz mnz nma.

     

On the rotational motion of deformable celestial bodies

¶rt;am au uu ¶rt; aam ¶rt;uu ¶rt;u ma; ¶rt;am am u ¶rt; a, ¶rt;a u¶rt; amua m uuu a; num n aaa auauu nm.     

Some possibilities of predicting radio wave absorption in the lower ionosphere

Summary An attempt is made to show possible ways of predicting radio wave absorption in the midlatitude lower ionosphere using relations between absorption and the intensity of solar ionizing radiation and/or common solar activity indices, and between absorption and f₀F2.

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aa mu nuau nu a¶rt;u ¶rt;um u u a mu ¶rt; nu u umum uuu uu (uu uu u¶rt;au amumu) u ¶rt; nu u f₀F2.