Natural light combines various sources of light, each with different wavelengths, amplitudes and propagation directions. Even light with an identical wavelength, amplitude and propagation direction may have a different direction of vibration. Light having a main component with some specific direction of vibration is called polarized light.

A water surface more intensely reflects light with horizontal polarization than with vertical polarization. Our eyes see the strong horizontally polarized light. The glimmering results from the synergy of the light intensity fluctuations from the water surfaces.