Sunlight glitter on a wind-ruffled sea: further studies.
Time-averaged intensities are computed for the glitter pattern of sunlight on a wind-ruffled sea. In the present work the azimuthally asymmetric form of the wave-slope distribution measured by Cox and Munk is used, so that the glitter pattern depends on the wind direction as well as magnitude. Results are calculated for both a clean ocean surface and one covered with an oil film. The glitter pattern is quite different with the oil film due to the quieting action of the oil on the waves, the greater reflectivity of the surface when oil is on the surface, and the larger values of polarization for the reflected light at most typical angles in the glitter pattern. These effects are illustrated and discussed as possible methods for the detection of oil slicks. The glitter pattern observed at satellite altitudes is also calculated.
The reflection of light in rippled surfaces
Summary The reflection of a distant source of light in a system of parallel ripples is seen as a slanting pillar of light, of which the inclination is calculated. The reflection in a system of circular ripples has the form of an hyperbola, passing through the regularly reflected image and the centre of the ripple system. Several every day observations may thus be understood. The method of calculation is general and applies to ripples, distributed according to any arbitrary law over a plane.
A Simple Optical Method for Measuring the Statistical Distribution of Water Surface Slopes
A flash-photography technique for determining the statistical distribution of slopes of wind-created waves is described. The technique consists of taking photographs with a flash camera directed vertically downward toward the water surface. The resulting photographs are flash reflection patterns that can be readily interpreted in terms of wave slopes. Wave-slope dispersion curves, as determined from daytime flash photographs taken from a bridge about 45 feet above the water, are given for wind velocities up to 20 knots. For example, the standard deviation of the across-wind wave slopes was found to be approximately 2.5, 5, and 7.8 degrees for wind velocities of 5, 10, and 20 knots, respectively. Under the same conditions the with-wind wave-slope standard deviation was found to be 4.2, 7.5, and 10 degrees.