Polarizers provide color and contrast enhancement. Reflected light often shows up as whitish glare that washes out color in an image. A polarizer corrects this problem producing deep, dramatically blue skies. It also removes glare from non-metallic surfaces, such as Windows and water. Color saturation in general, especially outdoors, can be improved significantly. Think of it as sunglasses for your camera. A Circular polarizer has the same effect as a polarizer and is used on cameras with beam splitting metering systems commonly found on auto focus slurs (for most 35mm auto-focus cameras see your camera manual).
area of sky most effectively polarized with a
Circular polarizer: point your Index finger at the sun. With your thumb extended at a right angle (90 Degree), rotate it around the axis of the Index finger. It will point out the band of deepest blue from horizon to horizon.