The method of investigating the sea wave spectra based on spectral processing of the sea surface images made at the diffused sky light is considered. The mechanisms of the sea surface image formation under the oblique viewing are discussed. It is shown that within the framework of a two-dimensional wave model and when the surface is illuminated by a clear sky, the sea surface image spectrum is proportional to that of the wave slopes' spectrum. Described is the developed in the Institute of Applied Physics, RAS optical incoherent light spectrum analyzer permitting to record two-dimensional spectra of the sea surface images in the real time mode. The spectrum analyzer has a wide dynamic range (up to 40-50 dB). The time required to record one two-dimensional spectrum is 1 sec. When the spectrum analyzer is set up at an oceanography platform or a ship bow, the devise can record the wave spectra ranging from 1 meter to several centimeters depending on the height above the sea level and the viewing angle. The method for reconstructing the wave spectrum absolute values using the test object spectrum is represented. Preliminary results of the wave spectra measurements carried out by the optical method (under different wind speeds) from the stationary oceanographic platform in Katsiveli and from a moving vessel are given. The drawn conclusion testifies to conformity of the obtained wave spectra to the available empiric information on the spectra within the wind wave range under consideration. The obtained wave energy angular distributions and the spectra features observed in the slicks are discussed. To study the features of wave spectrum dynamics, developed is the method for imaging the current two-dimensional wave spectra with high resolution of spatial frequency and wave direction. Time dependence of the wave angles' current spectra is represented as the horizontal bands; each of them corresponds to a certain direction of the wave propagation. At that the vertical direction in each band corresponds to the spatial frequency of the wave varying from short to long waves. The brightness of the images is proportional to the slope spectrum in the conventional color scale.

The brightness angular structure of the cloudless sky is studied based on the model of the sunlight single scattering. It is shown that the so-called near-horizon maximum of the sky brightness can be described within the framework of this model. Physical mechanism of arising of this maximum is analyzed; dependence of the maximum position on the light wavelength is explained. When the light wavelength increases, the sky brightness maximum "shifts" towards the horizon. It is related to the fact that the atmosphere optical thickness decreases with growth of a wavelength. These model data are compared to the experimental angular characteristics of the sky brightness obtained due to digital imaging of the horizon from the oceanographic platform. Possibility of estimating the atmosphere optical thickness using the angular position of the sky brightness near-horizon maximum is analyzed. Proposed is the algorithm for assessing the given characteristic for a certain value of the light wavelength based on graphical "inversion" of dependence of the angular distribution of the cloudless sky brightness upon the atmosphere optical thickness. The proposed algorithm and the horizon digital images permit to assess the atmosphere optical thickness in the R, G and B spectral ranges. The algorithm "robustness" to the errors in determining the sun azimuth relative to the observer is analyzed. The obtained estimates of the atmosphere optical thicknesses are in agreement with the known results of the nature measurements of the atmosphere analogous characteristics. The described method for reconstructing the values of the atmosphere optical thicknesses makes it possible to develop the applied sky brightness model taking into account multiple light scattering. The obtained values of optical thickness can be used in the models of angular distribution of the cloudless sky brightness to provide possibility of estimating the waves' statistical characteristics by the remote optical method.