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Durand, Loyal, Jr. (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume XXXI (1938)

Whitney, Lester V.
Transmission of solar energy and the scattering produced by suspensoids in lake waters,   pp. 201-221 ff. PDF (6.0 MB)


Page 201

 201TRANSMISSION OF SOLAR ENERGY AND THE 
SCATTERING PRODUCED BY SUSPENSOIDS 
IN LAKE WATERS* 
LESTER V. WHITNEY 
From the Limnological Laboratory of the Wisconsin Geological and 
Natural History Survey. Notes and reports No. 70. INTRODUCTION 
 The transmission of solar energy and the scattering produced by suspensoids
were measured for a number of northern Wisconsin lakes in the summer of 1936.
Readings of solar energy were taken as deep as possible with a thermopile,
and then overlapped and continued with a photoelectric cell. Energy curves
were plotted and transmissions calculated. A table was made up listing the
total transmissions corrected for 100 per cent zenith sun and the scattering
powers of the suspensoids. The method of correcting for zenith sun is described
in a paper by the author on the Measur~ement of Continuous Solar Radiation
in Wisconsin Lakes (1938). 
 All measurements of scattered light intensities were taken with the photocell
face down; the thermopile was not sensitive enough for these readings. The
usual procedure was to take a series of measurements with the thermopile
and photocell face up and then to follow immediately with the photocell face
down. Simultaneous readings were also made of sun and sky intensity incident
on the water surface; a solarimeter maintained in a horizontal position in
the boat was used for this purpose. Ratios of scattered light intensities
to direct light intensities from sun and sky were calculated for the various
depths. 
 The scattering coefficients of the suspended particles and the fractional
amounts scattered compared to the amounts of light purely absorbed, were
computed from the ratios of light intensities and from the total extinction
coefficients. These extinc 
* This investigation was supported by a grant from the Brittingham Trust
Fund. 


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