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Rozwiązano równanie dyfuzji wody ze stałym współczynnikiem dyfuzji w nieskończonej płycie. Rozkład zawartości wody w płycie jest paraboliczny. Wyznaczono równanie pozwalające obliczać gradienty zawartości wody na powierzchniach płyty.
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Wpływ czynników geograficznych na klimat Europy

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The main purpose of the study was to define the most important features of the climate of Europe, which derive from geographical position and altitude above sea level. To begin with, we discuss the thermal features of Europe's climate which result from the continent's location at moderate latitudes. The research was conducted on the basis of average monthly values of air temperature in 30-year periods, 1961-1990. The fields of real sunshine, air temperature, atmospheric precipitation, atmospheric pressure and wind velocity were described using empirical models - regression polynomials of the second degrees y = f (φ), y= f (λ), y = f (H) for three coordinates: latitude φ, longitude λ and altitude above sea level H. They simulate both the zonal variability of air temperature T(φ) and precipitations P(φ) (which depends on the incoming solar radiation) and the impact of the Atlantic Ocean and the altitude T(λ), P(λ). The equation of the regression hyperplane has been a good tool for the inverstigation of general features of Europe's climate: y = a₀ +a₁ φ+a₂ λ + a₃ H. Coefficients of partia! a₁, a₂, a₃ - are components of gradients of meteorological variables; a₁ - meridional gradient, in °C/1° φ; a₂ - latitudinal gradient, in °C/1 °λ; a₃ - hypsometric gradient, in °C/100 m.
Scale-dependency is one of the well-known features of ecological boundaries. Unfortunately, there are relatively few case studies analysing boundaries of different scales. Moreover, properties of moving split window (MSW) technique, a method potentially suitable for examining boundaries at several spatial scales, are not fully understood. In this study, we used artificial data sets to test the capacities and limitations of the MSW method. We also applied field data from the Mecsek Mts (Hungary) (611 m a.s.l.) in order to reveal possible boundaries at different scales and to contribute to the knowledge on vegetation pattern of mountain areas. We found that one should apply several window-widths when using MSW, since this is the only way to detect and differentiate between boundaries of different scales. Our study revealed the vegetation pattern of Mt Tubes: there is a series of continuously intergrading mesic communities on the northern slope, while the southern slope is occupied by a mosaic of different xeric communities. In this pattern, boundaries of two different scales have been identified. We conclude that MSW could effectively be used in similar mountain regions to analyse herb layer vegetation patterns and boundaries.
This study presents distribution and abundance of three Potamogeton species, namely Potamogeton crispus, P. nodosus and P. pectinatus along environmental gradients in the lowland river Wełna (NW Poland). The relationships between 13 environmental factors and the pattern aquatic vegetation distribution along river were investigated. Among ecological factors rarely undertaken in aquatic ecology the light climate was concerned. It is postulated that the Potamogeton communities in the investigated river are strongly connected with water velocity, substrate of bottom and light conditions, in particular dissolved organic matter (DOM). Elodeo-Potametum crispi and algae communities with dominant species Hildenbrandia rivularis were well developed in the places shading by trees, with high velocity and fairly clean water, mostly with stony bottom. Potametum nodosi was noted in mean values of velocity and medium water quality with high content of organic matter in the bottom substrate. The last investigated community Sparganio-Potametum interrupti was found in poor water quality with the highest values of electric conductivity. The obtained results give a new approach of the ecology and abiotic typology of rivers with macrophytes including abundance of Potamogeton species (Nature 2000 habitat, code 3260 – “Water courses of plain to montane levels with the Ranunculion fl uitantis and Callitricho-Batrachion vegetation”).
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