The angular distribution of underwater radiance for green light has been studied in the upper turbid layers of the Gullmar fjord by means of a radiance meter which is lowered in the sea along a guide wire with a fixed orientation. A theoretical discussion considers the different components entering into the light field, vir. direct sunlight, skylight, and scattered light. O n the basis of available measurements of the volume scattering function the scattered light is evaluated by integrating light scattered from the predominant sun beam alone. The experimental angular distributions of radiance compare well with the theoretical distributions. In particular it is demonstrated that the radiance in the angle interval rt 45' from the sun attains a maximum below the surface.
The angular distribution of underwater radiance for green light has been studied in the upper turbid layers of the Gullmar fjord by means of a radiance meter which is lowered in the sea along a guide wire with a fixed orientation. A theoretical discussion considers the different components entering into the light field, viz. direct sunlight, skylight, and scattered light. On the basis of available measurements of the volume scattering function the scattered light is evaluated by integrating light scattered from the predominant sun beam alone. The experimental angular distributions of radiance compare well with the theoretical distributions. In particular it is demonstrated that the radiance in the angle interval ± 45° from the sun attains a maximum below the surface.
We show that the generalised lattice animal model of Family and Coniglio naturally leads to a unified scaling picture for percolation and lattice animals in which the fugacity for occupied elements plays the dual role of a temperature-like and a field-like variable. Within this single-scaling-field description of percolation, there is only one independent exponent from which all others can be obtained. We define a new set of exponents a, p and y for percolation and find that they are all related to the cluster number exponent 0 through the relation C Y = y = 1 -p = 3 -0, in analogy with lattice animals. To relate the cluster radius exponent v to the other exponents we use the generalised Ginzburg criteria to obtain a modified hyperscaling relation for isotropic and directed, percolation and lattice animals. Using this relation we find that 0 -1 = q + vi(d -1) for directed percolation and 0 = vi(d -1) for directed lattice animals, where vi 1 and v I are exponents characterising the parallel and perpendicular cluster radii respectively. Using the same approach we obtain the Stauffer relation 0-1 =dv and the Parisi-Sourlas relation 0 -1 = (d -2)v for isotropic percolation and lattice animals respectively. The above relations give the following expressions for 0 within the Flory theory: O(perco1ation) = (3d +2)/(d +2), O(directed percolation) = (6d + 5)/(2d +4), O(anima1s) = (7d -6)/(2d +4) and O(directed animals) = 9(d -1)/(4d + 8). Stauffer D 1979 Phys. Rep. 54 1 Stauffer D, Coniglio A and Adam M 1982 Ado. Polym. Sci. 44 103 Wu F Y and Stanley H E 1982 Phys. Rev. Lett. 48 775 and J M J van Leeuwen (New York: Springer) p 169
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