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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. [1]-154 PDF (46.6 MB)


Page 153

 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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