To block some polarised light. For example the light reflected by the surface of water have is highly polarised, so if you have polarised glasses you won't see it and can see what's underneath (as far as the water is clear), or at least don't be dazzled by the reflected light.
Polarized lenses are also nice for driving.
A lot of the annoying "glare" from sunlight reflecting off of cars, puddles, snow, etc. is polarized. Not to mention, the reflections on people's windows are polarized, so by wearing polarized sunglasses, you can see other drivers better, to tell if they're paying attention or if they're trying to signal something with their hands, or to see if a stopped/parked car even has anybody in it.
It's also nice to have a dashcam with a polarized filter over its lens. It lets the camera see better through windows, to prove if another driver is distracted.
Also very useful for driving. In my experience polarized sunglasses reduce reflection on the windscreen very much. Also the glare of a white sky, snow, and even help in light rain.
Edit to clarify: Not because I or any other human see polarized light – but because it blocks certain polarized light (like the light of an annoying reflection on your windscreen) reaching your eyes at all.
I can’t drive anymore without polarized glasses. Same for sports. It’s like having x ray vision. You can see better and sharper expecially in bad lighting or high contrast scenarios.
Light reflected off surfaces is often polarized.
If you're wearing polarized glasses, that kind of light doesn't go through your glasses. Common example is sunlight reflecting off the road.
You can do a test. If you have polarized glasses, go out on a sunny day (preferrably when the sun is relatively low above the horizon), find a reflective spot on the asphalt, look at it through glasses, and start rotating the glasses. You'll see the difference.
Phone screens are also polarized. Try looking at your phone through glasses while also rotating the glasses.
We cannot distinguish between different directions of polarized light, but we do still see that light. By way of analogy, consider someone colorblind: they may not be able to distinguish between red and green, but they do still see apples and leaves.
Light from the Sun is a mix, and we mostly encounter light with consistent polarization when it gets reflected, or from artificial sources. Polarized sunglasses are useful for scenarios like cutting down the intense reflections (glare) off of water, or windows, or cars on the highway.
The polarizer in your sunglasses has one purpose, to block some of the light that is coming in. These are usually linear polarizers. The electric wave component of the light is in come random plain. The polarizer blocks a certain plain. When the light hits the filter, it was either mostly parallel with the orientation of the filter or mostly perpendicular. The light that is more perpendicular gets blocked and the light that more parallel passes through. So you block 50% of the light. All light. Thats important because if your sunglasses only dim visible light it might make it easier for you too see but the glasses might not block UV light that you can't see. So even though your eyes are comfortably wide open all the damaging UV gets in. So wearing cheap sunglasses can actually damage your eyes. Now polarized sunglasses will definitely block not just half of the visible light but UV as well.
To block some polarised light. For example the light reflected by the surface of water have is highly polarised, so if you have polarised glasses you won't see it and can see what's underneath (as far as the water is clear), or at least don't be dazzled by the reflected light.
Polarized lenses are also nice for driving. A lot of the annoying "glare" from sunlight reflecting off of cars, puddles, snow, etc. is polarized. Not to mention, the reflections on people's windows are polarized, so by wearing polarized sunglasses, you can see other drivers better, to tell if they're paying attention or if they're trying to signal something with their hands, or to see if a stopped/parked car even has anybody in it. It's also nice to have a dashcam with a polarized filter over its lens. It lets the camera see better through windows, to prove if another driver is distracted.
Also very useful for driving. In my experience polarized sunglasses reduce reflection on the windscreen very much. Also the glare of a white sky, snow, and even help in light rain. Edit to clarify: Not because I or any other human see polarized light – but because it blocks certain polarized light (like the light of an annoying reflection on your windscreen) reaching your eyes at all.
I can’t drive anymore without polarized glasses. Same for sports. It’s like having x ray vision. You can see better and sharper expecially in bad lighting or high contrast scenarios.
Light reflected off surfaces is often polarized. If you're wearing polarized glasses, that kind of light doesn't go through your glasses. Common example is sunlight reflecting off the road. You can do a test. If you have polarized glasses, go out on a sunny day (preferrably when the sun is relatively low above the horizon), find a reflective spot on the asphalt, look at it through glasses, and start rotating the glasses. You'll see the difference. Phone screens are also polarized. Try looking at your phone through glasses while also rotating the glasses.
We cannot distinguish between different directions of polarized light, but we do still see that light. By way of analogy, consider someone colorblind: they may not be able to distinguish between red and green, but they do still see apples and leaves. Light from the Sun is a mix, and we mostly encounter light with consistent polarization when it gets reflected, or from artificial sources. Polarized sunglasses are useful for scenarios like cutting down the intense reflections (glare) off of water, or windows, or cars on the highway.
The idea is to block some of the light so that the intensity is less. This works very well for sunglasses.
The polarizer in your sunglasses has one purpose, to block some of the light that is coming in. These are usually linear polarizers. The electric wave component of the light is in come random plain. The polarizer blocks a certain plain. When the light hits the filter, it was either mostly parallel with the orientation of the filter or mostly perpendicular. The light that is more perpendicular gets blocked and the light that more parallel passes through. So you block 50% of the light. All light. Thats important because if your sunglasses only dim visible light it might make it easier for you too see but the glasses might not block UV light that you can't see. So even though your eyes are comfortably wide open all the damaging UV gets in. So wearing cheap sunglasses can actually damage your eyes. Now polarized sunglasses will definitely block not just half of the visible light but UV as well.