Some examples of the effects of a circular polarizer.

Light reflected from surfaces at the Brewster angle is polarized. A polarizing filter placed in front of a camera lens can be tuned such as to filter out light of this particular polarization. Hence, the polarizing filter permits to filter out sunlight reflected from surfaces and particles, letting through the lens only light with non-zero components in the perpendicular plane of polarization. In an outdoor scene, sun light reflects from water, rocks, leaves, dust particles, etc. The polarizer cuts out this reflection, allowing water, rocks and leaves to be of a more saturated color (less of a white component in their color), and partially clears out the haze visible in air. Also, the blue of the skies is intensified, making the clouds stand out.

Because reflected light polarization only occurs at the Brewster angle, the effect of a polarizing filter is strongly dependant on the angle of the camera with respect to the sun and to the reflective surface.