Possibilities of agricultural settlements in the northern coastal area of Kenya —an analysis of relevant climatic factors     

Dr. Ralph Jaetzold 《GeoJournal》1978,2(3):225-242

Kenya is one of those African countries with a very high population pressure. In cultivatable areas we find up to 650 rural inhabitants per sq km. The search for new possibilities of agricultural settlement is an indispensable task. Many sciences are involved, also the geography of climates. Probably the largest potential settlement area from the climatic point of view is the Northern coastal zone. It has been settled in medieval times much more densely than today. War-like invasions of nomads have decreased the population since the 16th century. The average density of the cultivatable strip has been less than 5 inhabitants per sqkm in the last census year 1969. New settlement schemes have been developed since 1970, but they face the difficulty to choose the right varieties of crops. Careful climatic investigations are necessary for the further selection of areas and for the agricultural extension service. Here, only a first approach has been made. The main emphasis was laid on the effective rainfall in the so-called agrohumid period of the year and its probability. A new system of climatic classification was applied to give a frame for further, more specialised studies.  相似文献   

How long is coal's future?     

Ralph M. Rotty  Alvin M. Weinberg 《Climatic change》1977,1(1):45-57

Nearly all scenarios for future U.S. energy supply systems show heavy dependence on coal. The magnitude depends on assumptions as to reliance on nuclear fission, degree of electrification, and rate of GNP growth, and ranges from 700 million tons to 2300 million tons per year. However, potential climate change resulting from increasing atmospheric carbon dioxide concentrations may prevent coal from playing a major role. The carbon in the carbon dioxide produced from fossil fuels each year is about 1/10 the net primary production by terrestrial plants, but the fossil fuel production has been growing exponentially at 4.3% per year. Observed atmospheric CO₂ concentrations have increased from 315 ppm in 1958 to 330 ppm in 1974 - in 1900, before much fossil fuel was burned, it was about 290–295 ppm. Slightly over one-half the CO₂ released from fossil fuels is accounted for by the increase observed in the atmosphere; at present growth rates the quantities are doubling every 15–18 years. Atmospheric models suggest a global warming of about 2 K if the concentration were to rise to two times its pre-1900 value - enough to change the global climate in major (but largely unknown) ways. With the current rate of increase in fossil fuel use, the atmospheric concentration should reach these levels by about 2030. A shift to coal as a replacement for oil and gas gives more carbon dioxide per unit of energy; thus if energy growth continues with a concurrent shift toward coal, high concentrations can be reached somewhat earlier. Even projections with very heavy reliance on non-fossil energy (Neihaus) after 2000 show atmospheric carbon dioxide concentrations reaching 475 ppm.First presented to the symposium, Coal Science and our National Expectations, Annual Meeting of the American Association for the Advancement of Science, Boston, Massachusetts, February 20, 1976.  相似文献   

Fluorine in meteorites     

Ralph O. Allen  Patrick J. Clark 《Geochimica et cosmochimica acta》1977,41(5):581-585

Microanalysis using a resonant nuclear reaction was used to measure F concentrations in USGS standard rocks and 21 meteorites. The F appears to be a moderately depleted element, but there were significant variations within each sample. Measurements on separated metal phases suggest that about 20% of meteoritic F is in the metal or in a phase closely associated with it. Simultaneous measurements of F, Mg, Na, Al and Si in the non-magnetic fractions of meteorites suggest plagioclase as a F containing phase.  相似文献   

Finite-element method in modeling geologic transport processes     

Ralph Ta-shun Cheng  Dennis S. Hodge 《Mathematical Geology》1976,8(1):43-56

Deterministic mathematical modeling of complex geologic transport processes may require the use of odd boundary shapes, time dependency, and two or three dimensions. Under these circumstances the governing transport equations must be solved by numerical methods. For a number of transport phenomena a general form of the convective-dispersion equation can be employed. The solution of this equation for complicated problems can be solved readily by the finite-element method. Using quadrilateral isoparametric elements or triangular elements and a computational algorithm based on Galerkin's procedure, solutions to unsteady heat flux from a dike and seawater intrusion in an aquifer have been obtained. These examples illustrate that the finite-element numerical procedure is well suited for solving boundary-value problems resulting from modeling of complex physical phenomena.  相似文献   

Some models for the rate of crystallization of garnet in metamorphic rocks   总被引：1，自引：0，他引：1  

Ralph Kretz 《Lithos》1974,7(3):123-131

Information on the form of the equation for the rate of crystallization of garnet in metamorphic rocks may be obtained by combining an expression for the rate of crystal growth, obtained from data on compositional zoning, with an expression for the rate of nucleation, obtained from the crystal-size distribution.Three models for the rate of crystal growth and four for the rate of nucleation are formulated, and these, in different combinations, give rise to ten models for the rate of crystallization. Considerable variation in the form of the growth and nucleation equations produces a relatively small variation in the form of the equation for the rate of crystallization. In the favoured crystallization models, the volume of garnet produced in unit volume of rock is a function of time raised to the power m, where m lies between 3.5 and 5.  相似文献   

DISCUSSION OF "Testing'a Limestone Aquifer Using Water-Table Response to Storm Water Discharged into Sinkholes," by Andrew Michalski and Joseph Torlucci, Jr., November-December 1988 issue, v. 26, no. 6, pp. 751–760     

Ralph O. Ewers 《Ground water》1989,27(5):715-716

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Marine and estuarine shallow water science and management     

Francis J. Reilly  Ralph J. Spagnolo  Edward Ambrogio 《Estuaries and Coasts》1996,19(2):165-168

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Further Comments on Darcy Paper     

Ralph C. Heath 《Ground water》1994,32(6):1035-1035

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Phase relationship between sea level and abrupt climate change     

Francisco J. Sierro  Nils Andersen  Maria A. Bassetti  Serge Bern  Miquel Canals  Jason H. Curtis  Bernard Dennielou  Jose Abel Flores  Jaime Frigola  Beatriz Gonzalez-Mora  Joan O. Grimalt  David A. Hodell  Gwenael Jouet  Marta Prez-Folgado  Ralph Schneider 《Quaternary Science Reviews》2009,28(25-26):2867-2881

Direct traces of past sea levels are based on the elevation of old coral reefs at times of sea level highstands. However, these measurements are discontinuous and cannot be easily correlated with climate records from ice cores. In this study we show a new approach to recognizing the imprint of sea level changes in continuous sediment records taken from the continental slope at locations that were continuously submerged, even during periods of sea level lowstand. By using a sediment core precisely synchronized with Greenland ice cores, we were able to recognize major floods of the Mediterranean continental shelf over the past 270 kyr. During the last glacial period five flooding events were observed at the onset of the warmest Greenland interstadials. Consistent correspondence between warm climate episodes and eustatic sea level rises shows that these global flooding events were generated by pronounced melting of the Northern Hemisphere ice sheets, due to rapid intensification of Atlantic Meridional Overturning Circulation.The method described in this study opens a new perspective for inter-hemispheric synchronization of marine climate records if applied in other continental margins from the Southern Hemisphere or the equatorial regions.  相似文献   

Titan's Snowline     

Ralph D. LorenzJonathan I. Lunine 《Icarus》2002,158(2):557-559

We show that the “snowline” altitude on Titan, above which the condensed nonideal methane-nitrogen phase is solid, is lower (∼14 km) near the equator than at high latitudes (∼19 km). This counterintuitive result derives from the thermodynamic behavior of the binary condensate. The snowline altitude is an operating constraint on future Titan missions where icing would pose a ceiling on atmospheric flight. These snowline altitudes are higher than likely topography, suggesting that optically bright regions on Titan are not due to veneering caused by methane frost deposition.  相似文献