排序方式： 共有29条查询结果，搜索用时 15 毫秒
1.
2.
W. David Rust Donald R. MacGorman Eric C. Bruning Stephanie A. Weiss Paul R. Krehbiel Ronald J. Thomas William Rison Timothy Hamlin Jeremiah Harlin 《Atmospheric Research》2005,76(1-4):247
Balloon-borne electric field soundings and lightning mapping data have been analyzed for three of the storms that occurred in the Severe Thunderstorm Electrification and Precipitation Study field program in 2000 to determine if the storms had inverted-polarity electrical structures. The polarities of all or some of the vertically stacked charge regions in such storms are opposite to the polarities observed at comparable heights in normal storms. Analyses compared the charge structures inferred from electric field soundings in the storms with charges inferred from three-dimensional lightning mapping data. Charge structures were inferred from electric field profiles by combining the one-dimensional approximation of Gauss's law with additional information from three-dimensional patterns in the electric field vectors. The three different ways of inferring the charge structure in the storms were found to complement each other and to be consistent overall. Charge deposition by lightning possibly occurred and increased the charge complexity of one of the storms.Many of the cloud flashes in each case were inverted-polarity flashes. Two storms produced ground flash activity comprised predominantly of positive ground flashes. One storm, which was an isolated thunderstorm, produced inverted-polarity cloud flashes, but no flashes to ground. The positive and negative thunderstorm charge regions were found at altitudes where, respectively, negative and positive charge would be found in normal-polarity storms. Thus, we conclude that these storms had anomalous and inverted-polarity electrical structures. Collectively, these three cases (along with the limited cases in the refereed literature) provide additional evidence that thunderstorms can have inverted-polarity electrical structures. 相似文献
3.
4.
Is it hot in here or is it just me? Temperature anomalies and political polarization over global warming in the American public 总被引：1，自引：1，他引：0
Jeremiah Bohr 《Climatic change》2017,142(1-2):271-285
Do temperature anomalies affect political polarization over global warming? Americans’ attitudes about global warming are affected by whether they reside in states experiencing unseasonably warm (or cold) temperatures versus those experiencing milder temperatures. Specifically, in terms of causal attribution, political polarization over global warming is more pronounced in states experiencing temperature anomalies. Using pooled data collected during 2013–2014, this study utilizes logistic regression to explore how temperature anomalies exacerbate the political polarization among Americans over perceptions of whether global warming impacts are immediately evident as well as the attribution of global warming to human activity. Results indicate that very cold or warm temperature anomalies from a 5-year baseline predict perceptions of global warming impacts and exacerbate existing political polarization over the causal attribution of global warming. These effects are particularly noticeable among Democrats. This analysis provides a contribution to understanding how temperature anomalies from the recent past shape the sociophysical context of global warming attitudes. 相似文献
5.
6.
Abstract– Simulants of lunar dust are needed when researching the lunar environment. However, unlike the true lunar dust, today’s simulants do not contain nanophase iron. Two different processes have been developed to fabricate nanophase iron to be used as part of a lunar dust simulant. (1) The first is to sequentially treat a mixture of ferric chloride, fluorinated carbon, and soda lime glass beads at about 300 °C in nitrogen, at room temperature in air, and then at 1050 °C in nitrogen. The product includes glass beads that are gray in color, can be attracted by a magnet, and contains α‐iron nanoparticles (which seem to slowly lose their lattice structure in ambient air during a period of 12 months). This product may have some similarity to the lunar glassy agglutinate, which contains FeO. (2) The second is to heat a mixture of carbon black and a lunar simulant (a mixed metal oxide that includes iron oxide) at 1050 °C in nitrogen. This process simulates lunar dust reactions with the carbon in a micrometeorite at the time of impact. The product contains a chemically modified simulant that can be attracted by a magnet and has a surface layer whose iron concentration increased during the reaction. The iron was found to be α‐iron and Fe3O4 nanoparticles, which appear to grow after the fabrication process. This growth became undetectable after 6 months of ambient air storage, but may last for several years or longer. 相似文献
7.
8.
9.
10.
Ryan M. Phelps Charles Kerans Robert G. Loucks Rui O.B.P. Da Gama Jason Jeremiah David Hull 《Sedimentology》2014,61(2):461-496
An integrated sequence stratigraphic study based on outcrop, core and wireline log data documents the combined impact of Cretaceous eustacy and oceanic anoxic events on carbonate shelf morphology and facies distributions in the northern Gulf of Mexico. The diverse facies and abundant data of the Comanche platform serve as a nearly complete global reference section and provide a sensitive record of external processes affecting Cretaceous platform development. Regional cross‐sections across the shoreline to shelf‐margin profile provide a detailed record of mixed carbonate–siliciclastic strata for the Hauterivian to lower Campanian stages (ca 136 to 80 Ma). The study window on the slowly subsiding passive margin allows the stratigraphic response to external forcing mechanisms to be isolated from regional structural processes. Three second‐order supersequences comprised of eight composite sequences are recognized in the Valanginian–Barremian, the Aptian–Albian and the Cenomanian–Campanian. The Valanginian–Barremian supersequence transitioned from a siliciclastic ramp to carbonate rimmed shelf and is a product of glacial ice accumulation and melting, as well as variable rates of mid‐ocean ridge volcanism. The Aptian–Albian supersequence chronicles the drowning and recovery of the platform surrounding oceanic anoxic events 1a and 1b. The Cenomanian–Campanian supersequence similarly documents shelf drowning following oceanic anoxic event 1d, after which the platform evolved to a deep‐subtidal system consisting of anoxic/dysoxic shale and chalk in the time surrounding oceanic anoxic event 2. Each period of oceanic anoxia is associated with composite sequence maximum flooding, termination of carbonate shelf sedimentation and deposition of condensed shale units in distally steepened ramp profiles. Composite sequences unaffected by oceanic anoxic events consist of aggradational to progradational shelves with an abundance of grain‐dominated facies and shallow‐subtidal to intertidal environments. Because they are products of eustacy and global oceanographic processes, the three supersequences and most composite sequences defined in the south Texas passive margin are recognizable in other carbonate platforms and published eustatic sea‐level curves. 相似文献