Chromopsia at various underwater depths
Ravara, A.M.
Bollettino della Societa Italiana di Biologia Sperimentale 50(22): 1887-1890
1974
ISSN/ISBN: 0037-8771 PMID: 4462779 Document Number: 81314
White light diminishes by diffusion, absorption, reflection and refraction under water with alterations of the spectrum. Divers were provided with 7 different colored screens and immersed under water using a lake near Bogliesco (Italy) and in the Gulf of Genoa. The subjects indicated the colors perceived at depths from 1-50 m. They had artificial respirators and were immersed slowly in April and May with temperatures of 15.degree. at 30 m depth and 20.degree. on the surface. The red screen appeared to be orange from 1 m and at 5-6 m it turned to the color of grape, disappeared at 10-15 m and became brown and blackish below 15 m. Orange disappeared at 15-20 m, yellow at 15-20 m becoming first green, blue and then grey. Green, blue, indigo and violet disappeared at an average of 35 m. A layer of water 1 m thick absorbs 40% of the light energy in the red, 25% of the orange, 16% of yellow, 12% of green, 8% of blue, 3% of indigo and 1% of violet. The amount absorbed is thus proportional to the length of decreasing wave-length. The divers did not perceive white light under water and the variations of colors in water are caused by the diminution of the wave-length perceived.