Planetary Climates

2013 ◽  
Author(s):  
Andrew P. Ingersoll
Keyword(s):  
Current Knowledge ◽  
Chemical Processes ◽  
Physical Processes ◽  
Climate History ◽  
Planetary Satellite ◽  
Chemical Mechanisms ◽  
Term Evolution ◽  
Earth’S Climate ◽  
Physical And Chemical

This clear and concise introduction to planetary climates explains the global physical and chemical processes that determine climate on any planet or major planetary satellite—from Mercury to Neptune and even large moons such as Saturn's Titan. The book presents a tour of our solar system's diverse planetary atmospheres, providing a rich foundation on their structure, composition, circulation, climate, and long-term evolution. Although the climates of other worlds are extremely diverse, the chemical and physical processes that shape their dynamics are the same. As this book makes clear, the better we can understand how various planetary climates formed and evolved, the better we can understand Earth's climate history and future. Explaining current knowledge, physical and chemical mechanisms, and unanswered questions, the book brings the reader to the cutting edge of this field.

scholarly journals The role of biotic forces in driving macroevolution: beyond the Red Queen

2015 ◽  
Vol 282 (1808) ◽  
pp. 20150186 ◽  
Author(s):  
Kjetil L. Voje ◽  
Øistein H. Holen ◽  
Lee Hsiang Liow ◽  
Nils Chr. Stenseth
Keyword(s):  
Current Knowledge ◽  
Abiotic Factors ◽  
Empirical Work ◽  
Theoretical Work ◽  
Long Term Evolution ◽  
Red Queen Hypothesis ◽  
Red Queen ◽  
Extinction Rates ◽  
Term Evolution

A multitude of hypotheses claim that abiotic factors are the main drivers of macroevolutionary change. By contrast, Van Valen's Red Queen hypothesis is often put forward as the sole representative of the view that biotic forcing is the main evolutionary driver. This imbalance of hypotheses does not reflect our current knowledge: theoretical work demonstrates the plausibility of biotically driven long-term evolution, whereas empirical work suggests a central role for biotic forcing in macroevolution. We call for a more pluralistic view of how biotic forces may drive long-term evolution that is compatible with both phenotypic stasis in the fossil record and with non-constant extinction rates. Promising avenues of research include contrasting predictions from relevant theories within ecology and macroevolution, as well as embracing both abiotic and biotic proxies while modelling long-term evolutionary data. By fitting models describing hypotheses of biotically driven macroevolution to data, we could dissect their predictions and transcend beyond pattern description, possibly narrowing the divide between our current understanding of micro- and macroevolution.

scholarly journals Hydrodynamics of a small trained tidal inlet (Currumbin Creek, Australia)

2014 ◽  
Vol 39 ◽  
pp. 45-53 ◽  
Author(s):  
S. Shaeri ◽  
R. B. Tomlinson ◽  
A. Etemad-Shahidi ◽  
D. Strauss ◽  
L. P. Hughes
Keyword(s):  
Marginal Effect ◽  
Beach Profile ◽  
Physical Processes ◽  
Inlet Channel ◽  
Tidal Variation ◽  
Bathymetric Survey ◽  
Term Evolution ◽  
Nearshore Waves ◽  
Local Ecology

Abstract. Small tidal inlets are important features of coastal areas, in terms of provision of access from a back barrier water-body to the ocean as well as periodic circulation of fresh nutrients for the local ecology. Usually, dimensional and geometrical characteristics contribute significantly to morphological stability or instability of a particular inlet and necessitate an individual investigation of any desired location. In other words, generalized usage of previous empirical and experimental research of a different position can hardly be used for other places. In this regard, one of the powerful tools to understand the physical processes of a particular region is to collect as much field data as possible. Such a dataset is used to further analyse and explore the governing processes and can also be used for building a numerical computer model for supplementary studies. In this research, the results of a comprehensive field measurement at Currumbin Creek, Queensland, Australia are presented. This study is part of broader research to investigate the long term evolution of the Currumbin entrance and its adjacent beaches. Currently, an annual dredging campaign is needed to reduce the risk of flooding due to excess rainfall inundations and to maintain water quality. The majority of data were collected over a three month period consistent with the time of the 2012 dredging operation. However, due to the loss of some instrumentation, data collection for some of the parameters was repeated till the middle of May 2013. All collected data included: (1) nearshore waves and tide; (2) creek tidal variation; (3) creek flow discharge and velocity; (4) bathymetric survey of the creek; (5) beach profile evolution survey; and (6) sediment sampling. The measurement showed that the creek entrance is tidally dominated, with flood events having a major role in sediment transport into the creek. The nearshore stations' wave data illustrated the marginal effect of the beach curvature between updrift and downdrift stations. Thus, the historical dataset available from the updrift wave rider buoy will be selected to be used for future numerical modelling. Although changes of some beach profiles were comparatively insignificant, the dramatic changes of the profile lines nearby the inlet channel and also rapid bathymetric change of the flood shoal following the dredging completion are valuable information to better calibrate and interpret a local sediment modelling study for the next phase. Essentially, this evaluation needs to be considered for proposing any alternative maintenance activities.

scholarly journals Are the Fractionation Corrections Correct: Are the Isotopic Shifts for 14C/12C Ratios in Physical Processes and Chemical Reactions Really Twice Those for 13C/12C?

Radiocarbon ◽  
2011 ◽  
Vol 53 (4) ◽  
pp. 691-704 ◽  
Author(s):  
John Southon
Keyword(s):  
Chemical Reactions ◽  
Isotopic Fractionation ◽  
Theoretical Work ◽  
Chemical Processes ◽  
Physical Processes ◽  
Isotopic Discrimination ◽  
True Value ◽  
A Value ◽  
Isotopic Shifts ◽  
Physical And Chemical

Conventional radiocarbon calculations correct for isotopic fractionation using an assumed value of 2.0 for the fractionation of 14C relative to 13C. In other words, isotopic discrimination in physical and chemical processes is assumed to cause relative shifts in 14C/12C ratios that are exactly double those of 13C/12C. This paper analyzes a 1984 experiment that produced a value for the fractionation ratio in photosynthesis of 2.3, which is used to this day by some researchers in the fields of hydrology and speleothem geochemistry. While the value of 2.3 is almost certainly incorrect, theoretical work suggests that the true value may indeed deviate from 2.0, which would have significant implications for 14C calculations.

scholarly journals Relationship between snow microstructure and physical and chemical processes

2012 ◽  
Vol 12 (11) ◽  
pp. 30409-30541 ◽  
Author(s):  
T. Bartels-Rausch ◽  
H.-W. Jacobi ◽  
T. F. Kahan ◽  
J. L. Thomas ◽  
E. S. Thomson ◽  
...  
Keyword(s):  
Chemical Reactivity ◽  
Experimental Studies ◽  
Chemical Processes ◽  
Field Observations ◽  
Physical Processes ◽  
Micro Scale ◽  
Surface Disorder ◽  
Snow Microstructure ◽  
Physical And Chemical

Abstract. Ice and snow in the environment are important because they not only act as a host to rich chemistry but also provide a matrix for physical exchanges of contaminants within the ecosystem. This review discusses how the structure of snow influences both chemical reactivity and physical processes, which thereby makes snow a unique medium for study. The focus is placed on impacts of the presence of liquid and surface disorder using many experimental studies, simulations, and field observations from the molecular to the micro-scale.

The Migration of Radionuclides with Ground Water. A Discussion of the Relevance of the Input Parameters used in Model Calculations

1981 ◽  
Vol 11 ◽  
Author(s):  
Bror Skytte Jensen
Keyword(s):  
Radioactive Waste ◽  
Ground Water ◽  
Chemical Processes ◽  
Model Calculations ◽  
Input Parameters ◽  
Long Term Performance ◽  
Term Performance ◽  
Physical And Chemical ◽  
Take All

The plans for the disposal of radioactive waste leave very little time for testing long term performance of a repository so the evaluation of the hazards involved in the operation relies heavily on model calculations. It is therefore of utmost importance that these model calculations take all important parameters into account and are based on a thorough understanding of the possible physical and chemical processes in which the migrating species take part.

The Mars-94 and Mars-96 missions

1994 ◽  
Vol 349 (1690) ◽  
pp. 295-307 ◽  
Keyword(s):  
Solar System ◽  
Short Description ◽  
Chemical Processes ◽  
Scientific Instruments ◽  
Martian Surface ◽  
Surface Layers ◽  
The Past ◽  
Wide Range ◽  
Physical And Chemical

The main goal of Solar System studies in Russia for the next 10-15 years is Mars and the Mars-94 project is the first stage of this long-term space programme. In October 1994 it is planned to launch a spacecraft with the following components onboard: an orbiter, two small autonomous stations to be landed on the surface of Mars and two penetrators to analyse the underlying surface layers. The main scientific objectives of this mission are to investigate the evolution and contemporary physics of Mars, and to make, using various methods, a wide range of comprehensive studies of those physical and chemical processes which took place in the past and which continue there now. The payload of the Mars-94 orbiter includes 23 scientific instruments to study the Martian surface, the inner structure of the planet, its atmosphere, and its plasma envelope, as well as instruments for astrophysical studies. The next stage of the programme is a mission to Mars in 1996. At present the Mars-96 project includes a spacecraft with an orbiter, a Martian rover, a balloon, penetrators and small stations. A short description of the scenario, payload, and scientific objectives of these missions is presented in this paper.

scholarly journals Laboratory simulation of physical and chemical processes in interstellar ices

1997 ◽  
Vol 178 ◽  
pp. 331-340 ◽  
Author(s):  
W.A. Schutte
Keyword(s):  
Surface Reactions ◽  
Current Situation ◽  
Chemical Processes ◽  
Laboratory Simulation ◽  
Physical Processes ◽  
Atoms And Molecules ◽  
Interstellar Ice ◽  
Chemical Conditions ◽  
Uv Photons ◽  
Physical And Chemical

We review the techniques which are applied to study by means of laboratory simulation the chemical and physical processes taking place in ices in interstellar dense clouds. We summarize the current situation with regard to spectroscopy of interstellar ice analogs and with regard to the simulation of chemical processes such as modification of the ices by UV photons and surface reactions between reactive atoms and molecules. It is discussed how such data can be used to explore the potential of the icy mantles both as a record of the various chemical conditions that occur in dense clouds and as an environment for unique interstellar chemical processes.

The Theoretical Evaluation of Localised Corrosion in Radioactive Waste Canisters.

1986 ◽  
Vol 84 ◽  
Author(s):  
S.M. Sharland
Keyword(s):  
Experimental Data ◽  
Radioactive Waste ◽  
Growth Rates ◽  
Crevice Corrosion ◽  
Chemical Processes ◽  
Uniform Corrosion ◽  
Theoretical Evaluation ◽  
Input Parameters ◽  
Physical And Chemical

AbstractUnder repository conditions, it is likely that radioactive waste canisters will be subjected to both uniform and localised corrosion. Localised corrosion can take many forms depending on the precise physical and chemical environment of the metal at the time of attack, but generally the rates of penetration are much greater than those associated with uniform corrosion. The most likely forms under aerated repository conditions are pitting and crevice corrosion. To ensure adequate radionuclide containment an allowance for these rates must be included in the final canister dimensions. It is considered the best way to predict long term penetration rates is to develop mathematical models, which include all the physical and chemical processes necessary to describe the system and use experimentally determined input parameters relating to these processes. These models must then draw on further experimental data for validation over short timescales. In this paper, we discuss several techniques of modelling long term pit propagation in waste canisters. The complexity of the problem has lead to a number of physical and chemical approximations in the modelling. We investigate the applicability and ranges of validity of several of the more common approximations, both in our own models and in the literature, and compare the predictions with experimental pit growth rates. An investigatation of the sensitivity of the models to the various empirical input parameters indicates which need to be determined most accurately.

Porosity/Diffusivity And Alkali-Silica Reaction

1988 ◽  
Vol 137 ◽  
Author(s):  
Micheline Moranville-Resocurd
Keyword(s):  
Chemical Processes ◽  
Alkali Silica Reaction ◽  
Physical Processes ◽  
Alkali Ions ◽  
Water Imbibition ◽  
Corrosion Of Steel ◽  
Physical And Chemical ◽  
Secondary Chemical ◽  
And Diffusion

AbstractPhysical and chemical processes are responsible for the alkali-silica reaction in concrete. Physical processes include (i) migration of hydroxyl and alkali ions (ii) swelling by water imbibition of the alkali-silica gel produced, (iii) development of cracks. Chemical processes involve (i) neutralisation of acidic silanol groups and attack of siloxane bridges, both by OH- ions (ii) formation of an alkali silicate. These reactions result in a breakdown in the silica structure and diffusion of some silicate and impregnate the cement paste filling the capillary pores. The increase in permeability due to the opening and progression of cracks facilitates secondary chemical deteriorations like the formation of ettrinqite, carbonation and corrosion of steel reinforcement. Recent studies have emphasized the role of Ca(OH)2 preventing the dissolution or miqration of freed silica out of the structure. Only the removal of Ca(OH)2 is able to stop the expansion of concrete.The paper will present some new interpretations of alkali-silica reaction related to the diffusivity of various ions from the pore solution.

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