At this time of year, fishing can be difficult in the bright sunlight and good Polaroid sunglasses are essential both for our own protection and to aid our fishing. Polaroid has the ability to reduce significantly the glare from a water surface.
When light waves meet a mirror, nearly all of them are reflected but when light reaches a transparent material such as glass or water it has three options: it can pass through (transmission), it can be reflected or it can be absorbed. In practice, it does all three which is why you can get weak reflections from a windowpane as most of the light is transmitted through the glass.
Most of our light comes from the hot atoms on the surface of the sun and the orientation of each light wave is random. Some waves move from side to side, others up and down and any other orientation between these two. (Imagine holding one end of a rope while the person at the other end shakes it vertically or horizontally).
When light reaches
a water surface the horizontal waves are reflected while the vertical waves are transmitted. The manufacturers of Polaroid use this phenomenon to our advantage. Before the plastic has set solid it is stretched so that the billions of plastic molecules are arranged in lines rather like the teeth in a comb or the palings in a chestnut fence.
This plastic is now mounted in our sunglasses with the lines vertical. Horizontally vibrating light waves from a wet surface cannot pass through the vertical lines of the Polaroid so the glare from the wet surface is much reduced. A more mathematical approach shows that Polaroid works best when you are looking down into the water at an angle of 53 degrees.
Finally, you can observe the Polaroid effect by looking down into the water with your glasses on and rocking your head from side to side!!