8. VISION AND BIOLUMINESCENCE
251
layers have been made. Kampa and Boden (1954) demonstrated that
the behaviour of a scattering layer in the area of the San Diego Trough
off California was related to diurnal changes in submarine illumination.
Measurements of the intensity of submarine illumination at increasingly
greater depths did not correspond to calculated values because the
attenuation coefficient of the water column is not constant throughout
the column, the water for instance in the euphotic zone in summer
500
525
425
450
475
WovtiPnQln 4” m#
FIQ. 92. Penetration of sun- and sky-light into the sea. Right : spectra of transmitted
sunlight at 50 m intervals of depth in the Bay of Biscay (lat. 46”29’N, long. 7”59’W)
on 25 September, 1958 a t 1030-1130 G.M.T. Left: relation between depth and
irradiance at various wavelengths expressed as percentage of irradiance values at
the surface. The numbers at the ends of the curves indicate the wavelengths, in mp,
of maximum transmission of the interference filters used. (After Boden et al., 1960.)
being optically much denser than that in the lower parts of the column
(Kampa, 1955). Attenuation coefficients of sun- and sky-light have
been examined in the seas near the San Diego Trough, off Bermuda,
off Banyuls sur Mer in the Mediterranean (Kampa, 1961), in the Bay of
Biscay (Boden et al., 1960), in the northwestern Atlantic and the
Indian Oceans and in the Caribbean (Clarke and Backus, 1964 ; Clarke
and Kelly, 1964, 1965). These investigations, and there are others
which have not been quoted here, show that there are geographical,
seasonal, and vertical variations in the transparency and so in the
251
layers have been made. Kampa and Boden (1954) demonstrated that
the behaviour of a scattering layer in the area of the San Diego Trough
off California was related to diurnal changes in submarine illumination.
Measurements of the intensity of submarine illumination at increasingly
greater depths did not correspond to calculated values because the
attenuation coefficient of the water column is not constant throughout
the column, the water for instance in the euphotic zone in summer
500
525
425
450
475
WovtiPnQln 4” m#
FIQ. 92. Penetration of sun- and sky-light into the sea. Right : spectra of transmitted
sunlight at 50 m intervals of depth in the Bay of Biscay (lat. 46”29’N, long. 7”59’W)
on 25 September, 1958 a t 1030-1130 G.M.T. Left: relation between depth and
irradiance at various wavelengths expressed as percentage of irradiance values at
the surface. The numbers at the ends of the curves indicate the wavelengths, in mp,
of maximum transmission of the interference filters used. (After Boden et al., 1960.)
being optically much denser than that in the lower parts of the column
(Kampa, 1955). Attenuation coefficients of sun- and sky-light have
been examined in the seas near the San Diego Trough, off Bermuda,
off Banyuls sur Mer in the Mediterranean (Kampa, 1961), in the Bay of
Biscay (Boden et al., 1960), in the northwestern Atlantic and the
Indian Oceans and in the Caribbean (Clarke and Backus, 1964 ; Clarke
and Kelly, 1964, 1965). These investigations, and there are others
which have not been quoted here, show that there are geographical,
seasonal, and vertical variations in the transparency and so in the