Durand, Loyal, Jr. (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume XXXI (1938)
James, Harry Raymond; Birge, Edward A.
A laboratory study of the absorption of light by lake waters, pp. -154 PDF (46.6 MB)
James & Birge—Lake Waters and Light 153 sorption by pure water is given its full observed value. Figs. 29, 30 show remainder- curves of settled and filtered waters. 3. In Figs. 31, 32 remainder and factor curves are shown for the same waters that appear in Figs. 29, 30. M'arked irregularities appear in factor curves, 7000-8000 A; these are discussed on pp. 122-123. 4. Factor curves are based on percentile transmission of radiation, the complement of percentile absorption. Transmission ordinates for any curve plotted in the diagrams are measured downward from the 100 per cent line, taken as zero. Three types of such curves are used: the general factor curve, the color curve, and the suspensoid curve. The methods of computing ordinates for such curves are given in Table XIV, for the water of Nagawicka Lake. 5. The ordinates for the general factor curves are those percentile transmissions which, multiplied by those of pure water, will give as a product the percentile transmissions observed in the water examined. This method gives rise to 2-component analysis o-f absorption, shown in Figs. 33-36 and pp. 114-123. 6. The general factor curve of a settled lake water may be further analyzed and its transmission ordinates may be assigned to two components, color and susp-ensoids, these with water furnish the transmission ordinates for a 3-component analysis of total absorption of radiation by a settled lake water. In 3-component analysis of any water the factors are: A. Water as water. Highly selective in its action on light; maximum 7400-8000 A; minimum (1-2 per cent) 4000-.5500 A. B. Color. Highly selective. Maximum in short-wave spectrum, amount dependent on grade of color; minimum in long-wave spectrum, amount negligible for low colors. C. Suspensoids. Action on light comparatively non-selective; amount depend-ent on quantity of suspensoid present in the water. D. At any wave-length of the spectrum the product of the percentile transmissions for these three curves will equal that of the water examined, as found at that point. E. In Figs. 37-49 and accompanying text 3-component analysis of absorption of radiation in various waters is illustrated and discussed. 7. Any factor curve in these diagrams may be taken as a percentile absorption curve, showing the percentile effect which its factor or group of factors would have if operating alone on the
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