A search for either of those words produces many threads on sunglasses but I don't see this question addressed.
At what light level do polarized lenses start to be beneficial? For years I have worn a pair of prescription glasses with transitions polarized lenses when I leave the house pre-dawn and switch to darker polarized glasses when it gets bright out. It is time to replace my transition lenses for a new prescription and I am trying to decide if I want them polarized since I am usually wearing them in low light situations. The non-polarized version of the transitions get lighter as well as darker so they may be better suited for how I use them. On cloudy days I would just leave them on as long as I am not losing the ability to see the rocks under the surface.