|MadSci Network: Chemistry|
Dear John, All sunglasses should have UV protection, but not all sunglasses need to be polarized. UV is short for ultraviolet, which refers to a kind high energy electromagnetic radiation that we can't quite see. The wavelength of ultraviolet radiation is just a little shorter than the color violet. Anyway, because shorter wavelength electromagnetic radiation has more energy than longer wavelength, "visible light," it can damage your eyes. This is why you should always buy sunglasses with 100% UV protection. UVA and UVB refer to different wavelengths of ultraviolet radiation. UVA (ultraviolet A) is a little bit shorter than violet light, and UVB is even shorter than UVA. This means UVB has more energy than UVA and so can cause more damage to your eyes. The sun also emits UVC, which has even more energy, but your cornea pretty much blocks all of this by itself without sustaining any damage. Sooo, to cut to the chase, if you're going to be outside for a while, wear sunglasses that block 100% of the harmful UVA and UVB rays from the sun. Polarized sunglasses are a different treatment that's added to lenses to help block out glare off of objects like highways (important for driving) and water (important for you as you stare for hours waiting for one little fish). The polarization of light is a tricky subject to explain, so here's a good website that's a little technical: http://acept.la.asu.edu/PiN/rdg/polarize/ polarize.shtml Basically, light travels in waves. But all the waves aren't parallel to each other. Instead, light vibrates in planes that are spread 360 degrees around the clock. When light hits a reflector like water, what comes off is pretty much polarized so it's vibrating parallel to the ground. Polarized sunglasses block the concentrated waves that are reflected parallel, but they let the perpendicular rays pass through. These reflected waves are responsible for glare, so if you block those out,the glare is gone. But since you are still seeing waves aligned in the other directions, you can still actually see. But the important part is that it means polarized lenses will let you see into the water on sunny days. If it's not sunny out, then polarized lenses don't do you any good. If there is no glare, there's no point trying to block it out. As for what color of lens is best, this is a personal issue. I like dark brown lenses, but most people usually go with grey. This is because most sunglass manufacturers sell gray. I think brown lenses give you more contrast than gray and make the world look a little "happier." Test drive both types before you buy. For those grey, low contrast type of days, try out yellow lenses to sharpen up details. Make sure they still have ultraviolet protection, though, since UV radiation goes through clouds. I don't think the yellow will get you to be able to see into the water any better, but it will brighten things up. Hope that helps. Good luck fishing! Tom
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