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)
11~A LABORATORY STUDY OF THE ABSORPTION OF LIGHT BY LAKE WATERS PART I. PERCENTILE ABSORPTION OF RADIATION IN THE VISIBLE SPECTRUM HARRY R. JAMES INTRODUCTION The transmission of white light through a material medium is always accompanied by the loss of some of the radiant energy by absorption; that is, some of the energy is transformed into heat, chemical energy, or to some other frequency of radiation. When the light passes through a medium which transmits all wave-lengths uniformly the emergent light will still be white; but if some part, or parts, of the spectrum are absorbed more than others the phenomenon of selective absorption is observed by the absence, in the transmitted light, of the wave-lengths so absorbed and the medium will show a color that is determined by the wave-lengths transmitted. All transparent media exert a selective action in some part of the spectrum, though the action may not be in the visible region. Pure water exerts a selective action which varies greatly throughout the visible spectrum. It is very transparent to blue and violet but absorbs red very strongly. If a material which affects the transmissiOn of light in any way is mixed with the water, the effects of the water and of the material will be added and a new absorption spectrum will be given. The present study was undertaken at the suggestion of Dr. E. A. Birge, biologist of the Wisconsin Geological and Natural History Survey, with the purpose of investigating the selective action on light of waters from the inland lakes of Wisconsin, with particular reference to the effect of coloring matters contained in the waters. The work is part of the study of the transmission of radiation in the waters of inland lakes, which has for many years been conducted by Dr. Birge and Dr. C. Juday. They have been attempting to determine the quantity and the composition of the light found at various depths in these lakes; with
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