Kondensationskerne im Rahmen der Luftelektrizität

Zusammenfassung Die Rolle der Kondensationskerne im atmosphärischen Geschehen wird besonders deutlich, wenn man sich vorstellt, wie sich dieses Geschehen ohne Kondensationskerne abspielen würde: Es käme dann auf der ganzen Erde nur der globale Anteil der atmosphärisch-elektrischen Erscheinungen zur Geltung während die Bindungen zum Wettergeschehen fehlen würden. Somit hängt also der gestaltende Einfluß des Wetters auf die elektrischen Vorgänge ursächlich mit dem Vorhandensein von Suspensionen bezw. Kondensationskernen zusammen.Die atmosphärisch-elektrischen Ereignisse sind zu verstehen aus dem Zusammenwirken von Generatoren und veränderlichen Schaltelementen. In beiden Gruppen spielen die Kondensationskerne eine entscheidende Rolle, wie im einzelnen gezeigt wird:Die bekannten Zusammenhänge zwischen dem luftelektrischen Potentialgefälle und der atmosphärischen Leitfähigkeit einerseits und meteorologischen Elementen (Luftkörper, Turbulenz, Austausch, Inversionen u.a.) andererseits sind aus den Wiedervereinigungsbeziehungen zwischen Kleinionen und Suspensionen zu verstehen. Sie gehören in die Gruppe der veränderlichen Schaltelemente.An einem in den letzten Jahren beobachteten Effekt (Anstieg von Potentialgefälle und Vertikalstrom nach Sonnenaufgang), der seinem jahreszeitlich verschiedenen und von Ort zu Ort wechselnden Verhalten entsprechend als Austauschwirkung zu deuten ist («Austausch-Generator»), wird nach umfangreichen Untersuchungen an einigen Stationen der Schweizer Alpen die Mitwirkung der Kondensationskerne demonstriert. Diese scheint darin zu bestehen, daß Raumladungsbildungen in der Atmosphäre je nach dem Vorhandensein von Kondensationskernen in stärkerem oder geringerem Maße gewissermaßen zeitlich fixiert werden, sodaß der zur Generatorwirkung notwendige Transport dieser Ladungen durch Kräfte nicht-elektrischer Natur quantitativ durch die Kernzahl beeinflußt wird.

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Summary The role of the condensation nuclei in the atmospheric electrical processes becomes especially evident if it is imagined how this process would take place without condensation nuclei: On the entire earth only the global atmospheric electrical phenomena would become effective, while the relations to the weather processes would not exist. Thus, the influence of the weather on the electric processes is causally related with the existence of suspensions, resp. condensation nuclei.The atmospheric electrical processes are to be interpreted from the co-operation of generators and variabile circuit elements. In both groups the condensation nuclei play an important part as is shown here in detail:The known relations between the atmospheric electrical potential gradient and the atmospheric conductivity on one hand and meteorological elements [air masses, turbulence, exchange (Austausch), inversions, etc.] on the other hand must be understood by the recombination relations between small ions and suspensions. They belong to the group of variable circuit elements.As an effect observed in recent years (increase of the potential gradientand the air-earth-current after sunrise) which, corresponding to its behaviour varying at the different seasons and from place to place, must be interpreted as exchange (Austausch) effect («Austausch-Generator»), the co-operation of condensation nuclei is demonstrated on the basis of comprehensive investigations at some stations of the Swiss Alps. This seems to exist in the fact that space charge formations in the atmosphere may be transfered into a more stable, longer lasting state by the interaction of the condensation nuclei to a greater or smaller extent so that the transport of these charges by nonelectric forces necessary for the generator effect is quantitatively influenced by the number of nuclei.

     

Sur la chronologie des fronts froids

Résumé L'étude chronologique des fronts froids en Suisse romande fait apparaître: a) une faible variation annuelle de fréquence à deux maxima très peu prononcés en hiver et en été, et b) une variation diurne beaucoup plus accusée avec deux maxima vers 6 h et vers 16 h.

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Summary Chronological studies of the cold fronts in the French part of Switzerland reveal a) a feeble annual variation of frequency with two maxima only weakly pronounced in winter and summer, and b) a much larger diurnal variation with two maxima at 6 h and 16 h.

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Zusammenfassung Ein chronologisches Studium der Kaltfronten in der französischen Schweiz läßt a) eine schwache Jahresschwankung der Frequenz mit zwei nur schwach ausgedrückten Maxima im Winter und im Sommer, und b) eine bedeutend stärkere Tagesschwankung mit Maxima gegen 6 und 16 Uhr erkennen.

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Avec 2 Figures     

Proterozoic tectonic evolution and late Svecokarelian plate deformation of the Central Baltic Shield

The continental crust of the Central Baltic Shield evolved by accretion towards the west during the Svecokarelian orogeny 1700–2200 Ma ago. The following features are consistent with a plate tectonic mechanism involving subduction of oceanic crust below an Archean craton in the east: flysch-sediments with serpentinite masses and pillow lavas, linear high-grade metamorphic zones, island-arc type volcanic belts and late tectonic batholiths with porphyry type Cu-Mo deposits.Semi-consolidated new crust was affected by late Svecokarelian deformation (D_n) after 1850 Ma; NNE-trending folds with crenulation cleavage were overprinted on older structures together with associated NW trending ductile transcurrent shear zones that curve the F_n folds into gentle S and Z shapes. The late tectonic batholiths intruded partly at the same time as and partly after the D_n deformation.

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Zusammenfassung Die kontinentale Kruste des zentralen Baltischen Schildes entwickelte sich durch nach Westen gerichtetes Anwachsen während der Svecokarelischen Orogenese vor 1700 bis 2200 Ma. Die folgenden Erscheinungsformen lassen sich mit einem plattentektonischen Mechanismus in Einklang bringen, der Subduktion von ozeanischer Kruste unter einen Archaischen Kraton im Osten einschließt: Flysch-Sedimente mit Serpentinit-Massen und Kissenlaven, lineare hochmetamorphe Zonen, vulkanische Gürtel vom Inselbogen-Typ und spättektonische Batholithe mit porphyrischen Cu-Mo-Lagerstätten.Die halbkonsolidierte neue Kruste wurde durch späte Svecokarelische Deformation (D_n) nach 1850 Ma erfaßt; NNE-orientierte Falten mit Krenulationsschieferung wurden älteren Strukturen aufgeprägt in Verbindung mit NW-streichenden, plastischen Transcurrent-Scherzonen, die die F_n-Falten in sanfte S- und Z-Formen verbiegen. Die spättektonischen Batholithe intrudierten teils während, teils nach der D_n-Deformation.

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Résumé La croûte continentale du Boucher baltique central a évolué par voie d'accrétion vers l'ouest durant l'orogénie svécocarélienne 1700–2200 Ma. Les événements suivants sont en accord avec un mécanisme de tectonique de plaques impliquant la subduction d'une croûte océanique sous un craton archéen à l'est: sédiments flyschoïdes avec masses de serpentinite et de laves en coussins, zones linéaires à haut degré de métamorphisme, ceintures volcaniques du type guirlande d'îles et batholithes tectoniques tardifs avec gisements porphyriques de type Cu-Mo.La nouvelle croûte à semi-consolidée fut affectée par une déformation svécocarélienne tardive (D_n) postérieure à 1850 Ma. Des plis de direction NNE avec clivage de crénulation ont été superposés sur des structures plus anciennes, associés à des zones de cisaillement transcurrentes de direction NW qui ont incurvé les plis F_n suivant des formes en S et Z. Le batholithe tectonique tardif s'est mis en place en partie au même moment que, et en partie après, la déformation D_n.

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, , 1500–2200 . , , : ; ; - . , 1850 ; NNE- , , NW , , F_n S Z. , .

     

Large-eddy Simulation of the Dispersion of Solid Particles in a Turbulent Boundary Layer

A large-eddy simulation (LES) with the dynamic Smagorinsky-Germano subgrid-scale (SGS) model is used to study the dispersion of solid particles in a turbulent boundary layer. Solid particles are tracked in a Lagrangian way. The instantaneous velocity of the surrounding fluid is considered to have a large-scale part (directly computed by the LES) and a small-scale part. The SGS velocity of the surrounding fluid is given by a three-dimensional Langevin model written in terms of SGS statistics at a mesh level. An appropriate Lagrangian correlation time scale is considered in order to include the influences of gravity and inertia of the solid particle. Inter-particle collisions and the influence of particles on the mean flow are also taken into account. The results of the LES are compared with the wind-tunnel experiments of Nalpanis et al. (1993 J Fluid Mech 251: 661–685) and of Tanière et al. (1997 Exp in Fluids 23:463–471) on sand particles in saltation and in modified saltation, respectively.     

Ionospheric storm effects in the nighttime E region caused by neutralized ring current particles

During magnetic storms an anomalous increase in the ionization density of the nighttime E region is observed at low and middle latitudes. It has been suggested that this effect is caused by the precipitation of neutralized ring current particles. Here a coupled ring current decay-ionosphere model is used to confirm the validity of this explanation.     

La végétation macrophytique d'un lac hautement eutrophe du Plateau suisse: Le Baldegger See

The study of the qualitative and quantitative distribution of the Baldeggersee macrophytic vegetation is undertaken in 1980 with the help of colour aerial photographies and verification on the field. The comparison with old data allows then a short survey of the macrophytic evolution in relation to the eutrophication.      

Cristallochimie de l'owyheeite: nouvelles données

Résumé L'étude chimique comparée, à la microsonde électronique, d'owyheeite de treize gisements différents a révélé des fluctuations sensibles des teneurs en éléments majeurs, en liaison avec la nature des sulfosels associés, ainsi que la présence occasionnelle de différents éléments mineurs: Cu et As (très fréquents), Sn et Bi (moins fréquents), Tl et Se (exceptionnels). Compte tenu du mode de substitution de ces éléments mineurs, la projection des analyses dans le système Pb₂S₂–Ag₂S–Sb₂S₃ délimite un champ restreint de solution solide dont l'allongement s'accorde avec la substitution 2 Pb²⁺Ag⁺+Sb³⁺. Ce champ de solution solide englobe la composition de la variété téremkovite, mais exclue la formule donnée initialement parShannon. La formule Pb_10–2x Sb_11+x Ag_3+x S₂₈ (–0,13x+0,20) rend compte des termes à la résolution de la Ag/Sb maximal; l'obtention d'une formule plus générale reste subordonée à la résolution de la structure cristalline. Aucun élément mineur ne peut jouer à lui seul le rôle de stabilisateur de la structure, mais ce même rôle peut être joué complémentairement par différents éléments, tels que Cu et Sn. Les clichés de microdiffraction électronique montrent des phénomènes de sur-structure plus ou moins prononcés, en liaison avec la concentration en (Ag+Cu), ou avec le degré de finesse du maclage complexe spécifique de l'owyheeite.

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Crystal chemistry of owyheeite: New data

Summary Comparative electron microprobe study of owyheeite from thirteen ore deposits shows significant variations in the concentration of major elements. These can be correlated with the chemical composition of the associated sulfosalts. Sometimes, some minor elements may be present: Cu and As (very frequent), Sn and Bi (less frequent), Tl and Se (exceptional). Considering certain substitution rules for minor elements, the analyses plotted in the Pb₂S₂–Ag₂S–Sb₂S₃ system show a limited solid-solution field, the elongation of which follows the substitution 2 Pb²⁺Ag⁺+Sb³⁺. This solid-solution field includes the composition of the variety teremkovite, but excludes the initial formula for owyheeite proposed byShannon. The formula Pb_10–2x Sb_11+x Ag_3+x S₂₈ (–0.13x+0.20) describes compositional variation of members with the highest Ag/Sb ratio; a more general formula would require the determination of the crystal structure. No individual minor element appears to be responsible for stabilizing owyheeite. The stabilization may be due to a combined effect of two elements, such as Cu and Sn. Electron diffraction patterns show superstructure reflections which are related to the (Ag+Cu) concentration, as well as to the scale of the complex twinning characteristic of owyheeite.

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Avec 3 Figures     

The New SCIAMACHY Reference Solar Spectral Irradiance and Its Validation

This paper describes a new reference solar spectrum retrieved from measurements of the satellite instrument SCIAMACHY in the wavelength region from \(0.24~\upmu\mbox{m}\) to \(2.4~\upmu\mbox{m}\) and its comparison with several other established solar reference spectra. The SCIAMACHY reference spectrum was recorded early in the mission before substantial optical degradation due to the harsh space environment sets in. The radiometric calibration of SCIAMACHY, applied in this study, includes a physical model of the scanner unit. Furthermore, SCIAMACHY’s internal white light source (WLS) is used to correct for on-ground to in-flight changes. The resultant calibrated solar spectrum from SCIAMACHY is in good agreement with several available solar spectral irradiance (SSI) references in the visible spectral range. Strong throughput losses due to detector icing in the near infrared (NIR) are now adequately accounted for. Nevertheless, a deficit with respect to the ATLAS-3 composite and SORCE/SIM SSI is observed in the NIR. However, the SCIAMACHY solar reference spectrum agrees well with the recently re-evaluated SOLAR/SOLSPEC-ISS and recent ground measurements taken at Mauna Loa in the NIR.     

Geomorphic controls on floodplain sediment and soil organic carbon storage in a Scottish mountain river

River floodplains constitute an important element in the terrestrial sediment and organic carbon cycle and store variable amounts of carbon and sediment depending on a complex interplay of internal and external driving forces. Quantifying the storage in floodplains is crucial to understand their role in the sediment and carbon cascades. Unfortunately, quantitative data on floodplain storage are limited, especially at larger spatial scales. Rivers in the Scottish Highlands can provide a special case to study alluvial sediment and carbon dynamics because of the dominance of peatlands throughout the landscape, but the alluvial history of the region remains poorly understood. In this study, the floodplain sediment and soil organic carbon storage is quantified for the mountainous headwaters of the River Dee in eastern Scotland (663 km²), based on a coring dataset of 78 floodplain cross-sections. Whereas the mineral sediment storage is dominated by wandering gravel-bed river sections, most of the soil organic carbon storage can be found in anastomosing and meandering sections. The total storage for the Upper Dee catchment can be estimated at 5.2 Mt or 2306.5 Mg ha^-1 of mineral sediment and 0.7 Mt or 323.3 Mg C ha^-1 of soil organic carbon, which is in line with other studies on temperate river systems. Statistical analysis indicates that the storage is mostly related to the floodplain slope and the geomorphic floodplain type, which incorporates the characteristic stream power, channel morphology and the deposit type. Mapping of the geomorphic floodplain type using a simple classification scheme shows to be a powerful tool in studying the total storage and local variability of mineral sediment and soil organic carbon in floodplains. © 2019 John Wiley & Sons, Ltd.