Rainbows - another way of understanding polarization.
At the core of every pair of Polaroid sunglasses is a unique polarizing filter that blocks glare – reflected light that’s travelling in the horizontal direction. It’s this polarizing core that stops you from squinting in bright light. Edwin Land, founder of Polaroid Corporation, developed the first synthetic polarizer for commercial use in the late 1920s. He probably knew that up to 94% of rainbow light is polarized.
In basic terms, a rainbow is an arc of coloured light in the sky. They occur when the sun’s rays are refracted by rain. As the sunlight hits the back of the water drops, it becomes polarized. This is similar to what happens when sunlight reflects off a lake or river – except the surface isn’t horizontal. Because the rainbow is polarized tangential to the arch, the polarizing filter in your sunglasses will enhance the contrasts at the side of the rainbow and make the arch appear less distinct.