This helpful infographic explains how polarised sunglasses effectively block glare being reflected from flat shiny surfaces such as water, snow, ice or even car hoods.
When sunlight beams towards the ground, it’s neatly aligned and travelling in the same linear direction. But when the light hits any flat shiny surfaces such as water, it becomes condensed and horizontally orientated into what is called "glare." This type of light makes is painfully difficult to see, even whilst looking through regular sun lenses.
To block glare, polarised lenses contain a chemical film sandwiched within the layers of the lens construction. Upon the polariser are millions of chemically aligned molecules in neat vertical lines.
These lines create a filter of vertical slots through-which only vertically orientated sunlight can pass. This prohibits any horizontal light from entering through the lens to drastically reduce the amount of glare.
When the lens is cut and fitted to your sunglasses frame, the polariser filter must be positioned so they’re vertical to your face. If the lens was to be horizontally positioned, the filter would then let the glare through.
Polarised sunglasses are especially popular for sporting or driving applications as they help to alleviate the strain on your eyes during long periods of visual focus.
Regardless of the light condition, polarised sunglasses help to provide a more accurate representation of what you're looking at which is why they're often deemed as a superior type of sunglasses lens.