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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 13

 James & Birge—Lake Waters and Light 13 
sorption of radiation by water and its content as found in lakes and with
especial attention to the effect of color on radiation; in Part II, which
is nearly ready for the press, these percentile results are applied to a
standard solar energy curve, which shows the amount and the composition of
the solar energy delivered to the surface of the lake. Thus are determined
the changes in quantity and in composition which the energy spectrum suffers
as it penetrates the waters of lakes. In all of the study the unit of lake
water is taken as a stratum one meter in thickness; absorptions are stated
as percentages, not as coefficients of extinction. 
 In Part I of the report the main subjects discussed are as follows: 
1. A new study of the selective action of distilled water on the visible
spectrum. With this are presented results from other observers and a brief
account of the effect of temperature on the absorption of light by distilled
water. The results are given in tables and in Figs. 3-7. 
2. A study of the relations between lake waters and radiation in the visible
spectrum. It comprises more than 180 series of readings on waters, in different
conditions, from 50 lakes; in which were determined their percentile absorption
of radiation at 21 (or 22) wave-lengths of the spectrum. These were placed
from 4078 A (more rarely 3650 A) to 8000 A; thus covering the visible spectrum.
The determinations are reported in tables showing percentile absorption in
settled and filtered lake waters, and in dilutions made from waters of high
color. From these data curves of total percentile absorption have been prepared
and many of them are shown in Figs. 14-26. Two diagrams are also given to
show absorption from 3650 A to 8000 A in settled and filtered waters. 
3. Total percentile absorption is determined by the combined action of several
factors. For certain lake waters a partial quantitative analysis of these
factors has been made and illustrated by diagrams. In a 2-component analysis
total absorption is assigned to factors of two types, viz., pure water, whose
action is the same in all lakes; and the united effect of color, suspensoids,
and all other minor factors operating in the lakes. This division of total
absorption can be made in 


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