Precipitation patterns

The Liesegang ring formation may be considered as possible example of Turing phenomena. 

Liesegang patterns in flow reactors (CFUR, DPL, open ring reactor) 

Two-dimensional experiments [59] on periodic precipitation of PbCr04, CuCr04 and Hgl2 have been carried out with a simple and inexpensive Das-Pushkarna-Lall (DPL) flow reactor [60]. 

The reactor is open with respect to the flow of one reactant as the other electrolyte was taken in the gel. In this reactor, the concentration and level of the electrolyte in the empty space were always kept constant. The DPL reactor was further modified by Das and co-workers to make it open with respect to the flow of both the reactants [61]. 

In the modified open gel-ring reactor, a gel ring (Fig. 10.4b) separates the two electrolyte solutions, which are fed continuously at the same flow rates. These reactors 

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The ability to predict runoff and water availability is critical to water resources planners. However, the complex non-linearities of the hydrologic cycle make this an extremely difficult process. Even where precipitation is fairly well known, runoff prediction is a non-trivial problem, as land surface response depends as much (or more) on precipitation patterns and timing as on precipitation amount. The historical record of monthly rainfall and inflow at the Serpentine Dam, near Perth, Western Australia, provides an illustration of this sensitivity (Fig. 6-11a and b). 

Fig. 6-8 Annual precipitation patterns for the United States. Precipitation in inches (1 inch = 25.4 mm). (From Linsley et ah, 1982.)...

Ropelewski, C. F. and Halpert, M. S. (1987). Global and regional scale precipitation patterns associated with the El Nino/Southem Oscillation. Mon. Wea. Rev. 115,1606-1626. 

Organic acid fluorescence. In a similar manner to trace constituents, such as Mg, Sr and P, concentrations of organic acids present in speleothem calcite are sufficient to observe variation at temporal scales of less than annual in some cases (e.g.. Baker et al. 1993, Shopov et al. 1994). Organic acids (humic and fulvic) are formed in the soil by humification, and transported to the cave void by percolating waters where they are entrapped in precipitating carbonates. Under certain circumstances, where precipitation patterns are strongly seasonal and the nature of vadose percolation is such that seasonal mixing is incomplete, bands with different luminescent intensities can be differentiated after excitation with UV radiation. In other cases, bands are not observable but secular... 

Altered Precipitation Patterns causing More Severe Storm Damage. 

Ortoleva, P. (1984). The self-organization of Liesegang Bands and other precipitate patterns. In Chemical Instabilities Applications in Chemistry, Engineering, Geology and Material Science, ed. G. Nicolis F. Baras, pp. 289-97. Dordrecht Reidel. 

The large-scale multi-year precipitation patterns for the European alpine region as shown in Eigs. 6 and 7 can be summarized as follows [5] ... 

However, changes in the seasonality of snowmelt coupled with shifts in precipitation patterns may result in water shortages in the summer and autumn, especially in downstream regions. For the River Rhine, for instance, some scenarios show a decrease in total discharge of more than 50% at the German-Dutch border for the low-flow period in the autumn [78]. Moreover, the declining impact of snow and ice melt will increase the year-to-year variability of discharge in the summer and autumn. 

There are a variety of other climate changes that might be expected to occur simultaneously with changes in temperature. These include changes in precipitation, an increase in the mean sea level, and more variability in the climate. As discussed in detail in IPCC (1996), changes in precipitation patterns and cloudiness have been noted over the past approximately four decades and there is evidence that the sea level has risen by 10-25 cm. The IPCC document should be consulted for detailed evidence for these effects and their possible relationship to anthropogenic perturbations. 

Herbicides derived from point and nonpoint sources can be transported to streams by runoff from agricultural and urban areas, discharge from reservoirs and aquifers, and precipitation. The physiochemical properties of the triazine herbicides, as well as other factors such as usage, precipitation patterns, and farming practices, are important in determining the amounts and concentrations of these chemicals in streams. 

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