Electric charge separation in severe storms

This paper proposes a new model for thunderstorm electric field generation which directly utilizes the dynamic turbulent motion to separate the charges. Postulating a microphysical charge separation mechanism, such as is commonly accepted in most other theories, and which places a negative charge on the larger particles with a positive charge on the smaller ones, it is described how evaporation and cooling at the tops of small cumuli will release the positive charges as ions. These ions migrate to the surrounding cloud as the cooled parcel, with negatively charged particles in it, sinks down through the cloud. Since the sinking parcel contains mostly ice, it will be more buoyant than its surroundings when it reaches rising regions of water cloud, and hence should come to rest near the –10°C level. Thus the cloud will acquire an accumulation of negative charge at about this level before substantial hydrometeors begin falling out of it.     

Surface-active substances on rainwater and atmospheric particles

The surface tension lowering by surface-active substances has been measured on rainwater, melted snow, and dispersions of atmospheric particles in water, with a film balance and a tensiometer. The precipitation water was sampled during 1979, 1980, and 1981 in the city of Frankfurt/Main. From measurements with the film balance technique, normalized concentrations of insoluble and weakly soluble surface-active substances have been estimated. Soluble surface-active substances were determined from measurements with a tensiometer. It was found that the normalized concentration of theinsoluble and weakly soluble surface-active material on rainwater or melted snow shows a maximum during late spring of about 2.5 · 10⁻⁷ moles/l and a minimum during wintertime of about 5 · 10⁻⁸ moles/l. These concentrations are too low to influence significantly the condensation of water vapour on cloud droplets or the evaporation of water from them. Thesoluble surface-active material on rainwater or melted snow was found to have concentrations of the order of 2 · 10⁻⁶ moles/l. These concentrations are also too small to have a significant influence on cloud physical processes.     

Komatiites and nickel sulfide ores of the Black Swan area,Yilgarn Craton,Western Australia. 3: Komatiite geochemistry,and implications for ore forming processes

The Black Swan komatiite sequence is a package of dominantly olivine-rich cumulates with lesser volumes of spinifex textured rocks, interpreted as a section through an extensive komatiite lava flow field. The sequence hosts a number of nickel sulfide orebodies, including the Silver Swan massive shoot and the Cygnet and Black Swan disseminated orebodies. A large body of whole rock analyses on komatiitic rocks from the Black Swan area has been filtered for metasomatic effects. With the exception of mobile elements such as Ca and alkalis, most samples retain residual igneous geochemistry, and can be modelled predominantly by fractionation and accumulation of olivine. Whole rock MgO–FeO relationships imply a relatively restricted range of olivine compositions, more primitive than the olivine which would have been in equilibrium with the transporting komatiite lavas, and together with textural data indicate that much of the cumulus olivine in the sequence was transported. Flow top compositions show evidence for chromite saturation, but the cumulates are deficient in accumulated chromite. Chromite compositions are typical of those found in compound flow-facies komatiites, and are distinct from those in komatiitic dunite bodies. Incompatible trace element abundances show three superimposed influences: control by the relative proportion of olivine to liquid; a signature of crustal contamination and an overprint of metasomatic introduction of LREE, Zr and Th. This overprint is most evident in cumulates, and relatively insignificant in the spinifex rocks. Platinum and palladium behaved as incompatible elements and are negatively correlated with MgO. They show no evidence for wholesale depletion due to sulfide extraction, which was evidently restricted to specific lava tubes or pathways. The lack of correspondence between PGE depletion and contamination by siliceous material implies that contamination alone is insufficient to generate S-saturation and ore formation in the absence of sulfide in the assimilant. Contamination signatures in spinifex-textured rocks may be a guide to Ni-sulfide mineralisation, but are not entirely reliable in the absence of other evidence. The widespread vesicularity of the sequence may be attributable to assimilated water rather than to primary mantle-derived volatiles, and cannot be taken as evidence for primary volatile-rich magmas. The characteristic signature of the Black Swan Succession is the presence of highly localised disseminated sulfide within a sequence showing more widespread evidence for crustal contamination and interaction with its immediate substrate. This has important implications for the applicability of trace element geochemistry in exploration for komatiite-hosted nickel deposits.Electronic Supplementary Material Supplementary material is available in the online version of this article at Editorial handling: Peter Lightfoot     

人工增雨综合技术研究

"人工增雨综合技术预研究"项目对人工增雨云水资源的开发潜力、人工增雨的科学模型及其数值模拟、人工增雨监测识别技术、人工增雨催化作业技术、人工增雨外场试验的科学设计和南方夏季对流云人工增雨潜力区识别技术等方面进行了综合研究,在此基础上初步优选和集成了人工增雨成套技术,并在抗旱型和蓄水型人工增雨外场试验中进行了初步应用,取得了较好的实用效果.     

层积云覆盖的海洋边界层云详细微物理过程的数值模拟

文中建立了一个含显式分档的云微物理模式和辐射传输模式的一维 3阶湍流闭合模式 ,该模式可用于研究海洋边界层云中气溶胶和云的相互作用过程 ,同时提出了一种新的动力模式和微物理模式耦合方法 ,该方法可使动力模式中液态水相关项可以直接由微物理模式变量计算得到。作为模式的初步应用模拟了 2 0 0 1年APEX/ACE Asia在西太平洋上所观测到的一个个例。模拟结果和观测资料比较表明该模式基本上模拟出层积云覆盖的海洋边界层的基本结构     

Examining the aerosol indirect effect over China using an SO2 emission inventory

The relationship between SO₂ emissions and the effective particle radius of low-level water clouds (r_e) over China was investigated to determine anthropogenic effects on clouds. Sulfur dioxide emission values were obtained from a statistical inventory, and r_e origins were retrieved by satellite remote sensing on a 0.5° grid. Comparisons between annual mean SO₂ emissions and r_e showed generally decreasing r_e values, explained by the Twomey effect. The existence of the Twomey effect is supported by comparisons with simulated aerosol optical depths. Results further suggest that clouds over land show sensitivity to the Twomey effect as well as clouds over the ocean.     

The Consequences of the Oder Flood in 1997 on the Distribution of Polycyclic Aromatic Hydrocarbons in the Oder River

Changes in the levels and spatial distribution of PAHs as a consequence of the Oder flood in the summer of 1997 were investigated in post‐flood sediments from the Oder River and the Oder Lagoon. The aim of this study was to identify sources of the PAH pollution and in particular investigate polluted sites (“hot spots”) in the most highly suspected locations of the drainage area. Molecular indices based on isomeric PAH ratios and the ratio of the parent PAHs to methylated PAHs were used to distinguish between the pollution sources. Elevated levels of PAHs were discovered in the post‐flood sediments of the Oder River in comparison to the average regional values. Elevated concentrations of PAHs were also found in fluffy layer samples taken from the Oder Lagoon and the Pomeranian Bight in late August. The highest concentrations of PAHs were observed near power plants or roads with heavy traffic. Most of the contamination originates from high temperature pyrogenic sources with some slight overlays of petrogenic sources. These increased concentrations of pyrogenic origin may be attributable to flooding of municipal and industrial waste disposal areas in the Oder River drainage.     

星载微波辐射计反演洋面非降水云区云水总量的研究

云水总量(也可称为液水路径)是一个重要的气象学和云雾物理参数。星载微波辐射计是目前监测全球范围内云水总量分布和变化的最强有力的技术手段。但由于云水总量的实测资料太少,给反演研究带来很大的困难。在本工作中,根据微波辐射传输模式,模拟计算“人工”资料样本,建立了AMSR-E 18.7 GHz~36.5 GHz六个极化通道云天-晴天亮温差与云水总量的线性回归关系,初步对云水总量的反演作了定性的研究。     

Strong, localised country-rock contamination and partial homogenisation of a mafic magma: An example from west central Sweden

A dolerite sill cutting slightly older basalt in west-central Sweden shows a strong chemical variation (54% < SiO₂ < 73%) within a restricted area (< 100 × 100 m²). The linear correlation among almost all elements is extremely high; in addition, _NdT is strongly correlated with the SiO₂ content. Least-square hyperbolic-ratio and three-element ratio modelling (common denominator) suggests that most of the chemical variation is explained by mixing and/or micro-mingling. In all, we test 407 hyperbolas, of which 402 are fitted. The five ratio pairs, which could not be fitted to a hyperbola using a least-square fitting procedure, have the ratio Th / Eu in common. Testing the goodness of fit is problematic for hyperbolic distributions; for comparing purposes we sum the distances to chords approximating the hyperbola. Mobile and immobile elements behave similarly, suggesting that no elements are lost or added from outside the system. The data suggests that already the most mafic of the analysed rocks is a mixture of the ‘normal’ dolerite and a siliceous crustal rock. A mafic magma intruded into the base of the crust, where it fractionated resulting in a decreased Mg number. The magma was then contaminated with country rocks in an intermediate magma chamber due to country rock melting; during mixing/mingling almost no fractionation took place. The contaminated rock suggests the presence of a fluid phase. This was probably a prerequisite for country-rock melting. Enrichment in some incompatible elements suggests that besides major mixing/mingling a thermochemical separation process has affected the most felsic rock enriching it in light rare earths and Zr.     

Barium anomaly in Kupa River drainage basin

The objective of this work is to present an example of environmental impact of barite waste management observed in stream sediments of the western part of the Kupa River drainage basin. It is a significant water resource for Croatia and a part of Slovenia. In addition, it is for both countries a region of tourism, sport and fishing. Sediments (fraction < 63 μm) collected within the whole drainage basin have shown a significant barium anomaly in the western part. The highest concentration of total barium (5790 mg/kg) was determined in Kupica, a tributary of Kupa River. The barium anomaly was traced in Kupa River about 120 km downstream. Looking for the contamination source it was found that the anomaly originates from uncareful waste disposal into an abyss, after barite separation in Homer (Lokve), Gorski Kotar, Croatia. From there barite entered Kupica River subterraneous. Barite and albite were identified by XRD near the source of Kupica River as minor minerals, while quartz and dolomite ferroan were major minerals. This preliminary report does not give yet an answer about barium solubility in river water, about its bioavailability and consequently about barium pollution in the western part of the Kupa River drainage basin, however the possibility is highlighted and discussed.