Über den „Taucheffekt” bei der Lichtmessung über und unter Wasser     

Franz Berger 《Theoretical and Applied Climatology》1961,11(2):224-240

Zusammenfassung Das Verhältnis der meßbaren Intensitäten in einem Lichtmeßgerät flacher Bauart dicht unter und über Wasser wird Taucheffekt genannt. Dieses Verhältnis weicht von der wahren Relation der Lichtintensitäten innerhalb weiter Grenzen ab. Entsprechend den verschiedenen optisch-geometrischen Bedingungen bei Opal-, Klarglas- und Mattscheiben gibt es drei verschiedenartige Taucheffekte.Opal- und Mattscheiben verhalten sich gegensätzlich, ihre Taucheffektbereiche liegen unterhalb, bzw. oberhalb des gut definierbaren Klarglaswertes. Dieser bildet für Opalglas die obere, für Mattglas die untere Grenze. Die untere Grenze für Opalglas ist annähernd bestimmt, die obere Grenze für Mattglas nicht. Kunststoffgläser mit ihren niedrigeren Brechungszahlen ergeben noch breitere Taucheffektbereiche als Silikatgläser.Das Verhältnis der tatsächlichen Intensitäten liegt im Bereich des Opalglas-Taucheffekts. Es muß daher möglich sein, ein Opalglas herzustellen, mit dem ein Lichtmeßgerät über und unter Wasser richtig zeigt.Opal- und Mattgläser weisen einen Oberflächeneffekt, d. h. einen Totalreflexionsfehler in der Nähe der Wasseroberfläche auf, dessen Zusammenhang mit dem Taucheffekt geklärt wird.Es wird eine einfache Vorrichtung angegeben, um bei Taucheffekt-Bestimmungen den Totalreflexionsfehler zu vermeiden.

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Summary The ratio of light intensities just below and above a water surface as measured by a light meter of disk-shaped design is called immersion effect. This ratio differs within a wide margin from the ratio of the true intensities. According to the different optical-geometrical conditions of light transmission through opal, clear and ground glass three different types of the immersion effect can be distinguished.The immersion effect of opal glass is lower, and that of ground glass higher than the (well defined) value for clear glass. The latter is the upper margin for opal glass, and the lower margin for ground glass. The lower margin for opal glass is approximately defined while the upper margin for ground glass is indefinite. Plastic glasses with their low index of refraction cause an even wider range of the immersion effect than silicate glasses.The true ratio of light intensities lies within the range of the immersion effect of opal glass. Therefore, it should be possible to design a light meter with an opal filter which gives correct readings above and below the water surface.When placed closely beneath the water surface opal and ground glass show an additional surface effect. It is caused by total reflection at the water surface. Its relation to the immersion effect is discussed.A simple device is described which eliminates the surface effect and permits accurate determinations of the immersion effect.

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Résumé Le rapport entre les intensités mesurées par un photomètre plat directement sous la surface de l'eau et au-dessus de celle-ci est appelé «effet de plongée»; il diffère de la relation véritable des intensités lumineuses dans de larges limites. Par suite des propriétés optiques différentes des disques de verre opalin, transparent ou mat, il existe trois effets de plongée différents.Les disques opalins et mats se comportent de façon contraire; leurs domaines d'effet de plongée se trouvent au-dessous et au-dessus de la valeur bien définie correspondant au verre transparent. Celle-ci constitute pour le verre opalin la limite supérieure, pour le verre mat la limite inférieure. La limite inférieure pour le verre opalin est à peu près définie, la limite supérieure pour le verre mat ne l'est pas. Les verres synthétiques à indices bas ont des domaines d'effet de plongée encore plus larges que les verres à silicates.Le rapport véritable des intensités se trouve dans le domaine de l'effet de plongée du verre opalin. Il doit donc être possible de préparer un verre opalin à l'aide duquel un photomètre fonctionne correctement dans et sur l'eau.Les verres opalins et mats présentent un «effet de surface», c'est-àdire une erreur de réflexion totale au voisinage de la surface de l'eau, dont on explique la relation avec l'effet de plongée.On donne un dispositif simple permettant d'éviter l'erreur de réflexion totale.

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Mit 11 Textabbildungen

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Diese Arbeit ist dem Andenken anFranz Sauberer gewidmet. Sie enthält manche Antwort auf methodische Grundfragen, um deren KlärungSauberer stets gewissenhaft bemüht war. Dem lieben, unvergessenen Kollegen sei damit wenigstens in memoriam der Dank erstattet, den ihm der Verfasser für Anregung und Kritik schuldet.  相似文献   

Dynamics and driving mechanisms of asymmetric human water consumption during alternating wet and dry periods     

Fuqiang Tian  You Lu  Hongchang Hu  Wolfgang Kinzelbach  Murugesu Sivapalan 《水文科学杂志》2020,65(Z3):507-524

ABSTRACT

Increases in human water consumption (HWC) and consequent degradation of the ecological environment are common in arid regions. Understanding the mechanisms behind these processes is important for sustainable development. Analyses of changes in HWC between alternating wet and dry periods are carried out in four arid inland basins in Central Asia and China (Syr Darya, Tarim, Heihe and Shulehe river basins). Based on runoff records, the presence of an asymmetric HWC response is proved (p < 0.01), with an increase in HWC during wet periods and a muted decrease during subsequent dry periods. This behaviour is interpreted by invoking theories from behavioural economics at the individual and community levels. A simple model based on these theories is shown to be able to reproduce the observed dynamics and is used to discuss the importance of strengthening institutional factors for water sustainability.  相似文献   

The galactic centre     

Wolfgang Kundt 《Astrophysics and Space Science》1990,172(1):109-134

An attempt is made to present all the relevant observations of our galactic centre and to explain them by means of a working scheme that involves a minimum number ofad hoc assumptions.In this scheme, the central engine is Sgr A^*, a supermassive star of some 10³ M and surface temperature 3.6×10⁴ K in Keplerian rotation, fuelled by the strongly magnetized disk. It drives both a non-thermal (pair-plasma) wind and a thermal wind. Interactions with the central star cluster and with the circumnuclear disk give rise to the thermal vortex Sgr A West and to the non-thermal spill-over bubble Sgr A East. The relativistic pair plasma escapes supersonically through the galactic chimney into the galactic twin jets, as in Seyfert galaxies.  相似文献   

U–Pb zircon and microfabric data of (meta) granitoids of western Cameroon: Constraints on the timing of pluton emplacement and deformation in the Pan-African belt of central Africa     

Gautier Njiekak  Wolfgang Drr  Jean-Pierre Tchouankou  Gernold Zulauf 《Lithos》2008,102(3-4):460-477

Striking characteristics of the western Neoproterozoic belt of Cameroon (NFBC) are the large volume of granitoids and crustal-scale shear zones. New structural and geochronological data from this area are provided to put constraints on the tectonic evolution of this segment of the belt and to make further correlations between major shear zones exposed on both sides of the Atlantic Ocean.

Three different complexes have been identified in the study area: the migmatitic complex of Foumbot (MCF), the metagranitoid complex of Bangwa (BC), and the Batié pluton (BP). The MCF was intruded by the BC, while the BP cuts through the BC. U–Pb zircon dating of metaleucogranite and metagranodiorite of the BC yielded concordant to subconcordant ages of 638 ± 2 Ma and 637 ± 5 Ma, respectively. A concordant U–Pb zircon age of 602 ± 1.4 Ma has been obtained from porphyrogranite of the BP. These ages are interpreted as emplacement ages. Continuous deformation from magmatic to solid-state flow along the BP margins and the (sub)parallelism of the steep solid-state foliation in the BP margins with the foliation in the surrounding BC and MFC suggest synkinematic emplacement of the BP along crustal-scale NNE to ENE-trending strike–slip shear zones. Subhorizontal foliations in migmatitic-gneiss xenoliths found in the BC suggest that the major transcurrent motion was preceded by thrusting.

The new data confirm previous assumptions that the western NFBC is equivalent to parts of the Borborema province of Brazil. There are geochronological correlations between the studied (meta)granitoids and Brasiliano pre- to syn-transcurrent granitoids of the Borborema province.  相似文献   

Cenomanian-Turonian high-resolution biostratigraphy of north-eastern Mexico and its correlation with the GSSP and Europe     

Christina Ifrim  Wolfgang Stinnesbeck 《Cretaceous Research》2008,29(5-6):943

Thin-bedded and millimetrically laminated platy marly limestone quarried near Vallecillo, north-eastern Mexico, contains abundant excellently preserved marine fossils. Planktic foraminifers, inoceramids, and ammonites occur throughout the 7.7-m-thick section of this plattenkalk and provide a precise and detailed biostratigraphic zonation from the uppermost Cenomanian to early Turonian, with a mixed assemblage of Tethyan and Western Interior Seaway faunal elements. Five species of inoceramids are present and described herein: Inoceramus pictus pictus, Mytiloides hattini, M. puebloensis, M. goppelnensis, and M. kossmati. The faunal characteristics of the Vallecillo fossil assemblage combined with the monotonous lithology are favourable attributes for correlation with the GSSP at Pueblo, Colorado, and the Eastbourne section in southern England. The first appearances (FAs) of Watinoceras and Mammites nodosoides are considered approximately isochronous and thus suited for long-distance correlation. In contrast, the FAs of Pseudaspidoceras flexuosum, Fagesia catinus, and Helvetoglobotruncana helvetica are clearly diachronous. The range of M. kossmati needs further evaluation.  相似文献   

Sédimentologie et paléontologie des paléoenvironnements côtiers rupéliens de la Molasse marine rhénane dans le Jura suisse     

Laurent Picot  Damien Becker  Lionel Cavin  Claudius Pirkenseer  Frédéric Lapaire  Gaëtan Rauber  Peter A. Hochuli  Silvia Spezzaferri  Jean-Pierre Berger 《Swiss Journal of Geoscience》2008,101(2):483-513

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Miocene emplacement and rapid cooling of the Pohorje pluton at the Alpine-Pannonian-Dinaridic junction,Slovenia     

László I. Fodor  Axel Gerdes  István Dunkl  Balázs Koroknai  Zoltán Pécskay  Mirka Trajanova  Péter Horváth  Marko Vrabec  Bogomir Jelen  Kadosa Balogh  Wolfgang Frisch 《Swiss Journal of Geoscience》2008,101(1):255-271

New laser ablation-inductive coupled plasma-mass spectrometry U-Pb analyses on oscillatory-zoned zircon imply Early Miocene crystallization (18.64 ± 0.11 Ma) of the Pohorje pluton at the southeastern margin of the Eastern Alps (northern Slovenia). Inherited zircon cores indicate two crustal sources: a late Variscan magmatic population (~270–290 Ma), and an early Neoproterozoic one (850–900 Ma) with juvenile Hf isotope composition close to that of depleted mantle. Initial εHf of Miocene zircon points to an additional, more juvenile source component of the Miocene magma, which could be either a juvenile Phanerozoic crust or the Miocene mantle. The new U-Pb isotope age of the Pohorje pluton seriously questions its attribution to the Oligocene age ‘Periadriatic’ intrusions. The new data imply a temporal coincidence with 19–15 Ma magmatism in the Pannonian Basin system, more specifically in the Styrian Basin. K-Ar mineral- and whole rock ages from the pluton itself and cogenetic shallow intrusive dacitic rocks (~18–16 Ma), as well as zircon fission track data (17.7–15.6 Ma), gave late Early to early Middle Miocene ages, indicating rapid cooling of the pluton within about 3 Million years. Medium-grade Austroalpine metamorphics north and south of the pluton were reheated and subsequently cooled together. Outcrop- and micro scale structures record deformation of the Pohorje pluton and few related mafic and dacitic dykes under greenschist facies conditions. Part of the solidstate fabrics indicate E–W oriented stretching and vertical thinning, while steeply dipping foliation and NW–SE trending lineation are also present. The E–W oriented lineation is parallel to the direction of subsequent brittle extension, which resulted in normal faulting and tilting of the earlier ductile fabric at around the Early / Middle Miocene boundary; normal faulting was combined with strike-slip faulting. Renewed N–S compression may be related to late Miocene to Quaternary dextral faulting in the area. The documented syn-cooling extensional structures and part of the strike-slip faults can be interpreted as being related to lateral extrusion of the Eastern Alps and/or to back-arc rifting in the Pannonian Basin.  相似文献   

Sea level in the late Quaternary: patterns of variation and implications     

W. H. Berger 《International Journal of Earth Sciences》2008,97(6):1143-1150

Studies of oxygen isotopes in foraminifers from deepsea sediments yield information about rates of change of sea level, for hundreds of thousands of years with a resolution of roughly 1,000 years. The statistics regarding fluctuations for the late Quaternary (the last 900,000 years) suggest that a rise of 10 m per 1,000 years (1 m per century) is not unusual, even when the system resides within a warm stage, as now. Values near 2 m per century, while rare, are well within the range of a warm system, beyond the 5-percentile of the overall range. Once sea level is near +10 m, further rise becomes highly unlikely within the conditions of the late Quaternary, suggesting the presence of some kind of natural barrier; that is, lack of vulnerable ice. The present volume of ice generally considered vulnerable (Greenland and West-Antarctic ice sheet) adds up (roughly) to the observed limit.  相似文献   

Temporal variations and trends of CFC11 and CFC12 surface-water saturations in Antarctic marginal seas: Results of a regional ocean circulation model     

Christian B. Rodehacke  Wolfgang Roether  Hartmut H. Hellmer  Timothy Hall 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(2):175-198

The knowledge of chlorofluorocarbon (CFC11, CFC12) concentrations in ocean surface waters is a prerequisite for deriving formation rates of, and water mass ages in, deep and bottom waters on the basis of CFC data. In the Antarctic coastal region, surface-layer data are sparse in time and space, primarily due to the limited accessibility of the region. To help filling this gap, we carried out CFC simulations using a regional ocean general circulation model (OGCM) for the Southern Ocean, which includes the ocean–ice shelf interaction. The simulated surface layer saturations, i.e. the actual surface concentrations relative to solubility-equilibrium values, are verified against available observations. The CFC surface saturations driven by concentration gradients between atmosphere and ocean are controlled mainly by the sea ice cover, sea surface temperature, and salinity. However, no uniform explanation exists for the controlling mechanisms. Here, we present simulated long-term trends and seasonal variations of surface-layer saturation at Southern Ocean deep and bottom water formation sites and other key regions, and we discuss differences between these regions. The amplitudes of the seasonal saturation cycle vary from 22% to 66% and their long-term trends range from 0.1%/year to 0.9%/year. The seasonal surface saturation maximum lags the ice cover minimum by two months. By utilizing observed bottle data the full seasonal CFC saturation cycle can be determined offering the possibility to predict long-term trends in the future. We show that ignoring the trends and using instead the saturations actually observed can lead to systematic errors in deduced inventory-based formation rates by up to 10% and suggest an erroneous decline with time.  相似文献   

Spectral measurements of aerosol particle extinction in the 0.4–3.7 μm wavelength range, performed at Sagres with the IR‐RAD sun‐radiometer     

Vito Vitale  Claudio Tomasi  Wolfgang Von Hoyningen&#;huene  Ubaldo Bonafe  Stefano Marani  Angelo Lupi  Alessandra Cacciari  Pietro Ruggeri 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):716-733

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