[Terriergal]

Water and ice don't absorb ultraviolet radiation at all, except in the 'vacuum UV' region where oxygen and nitrogen block it as well. On the other hand, your SPF 45 absorbs virtually all of it.

So there aren't any harmful rays that water would block from the sun in that 80 (?) percent of the sun's energy that it reflects?

Trying to figure out how I can get sunburned from the reflection off the snow and water if it doesn't reflect those things.

[Right Wing Professor]

You're confusing reflection with absorption.

When light hits something, it can be transmitted, absorbed or reflected. Whatever fraction UV is reflected, a similar fraction of visible light would be reflected. So, sure, a shiny surface above the earth could reflect 80% of the UV, but only if it reflects about 80% of the visible light. Without visible light, plants don't grow. What you want is to absorb the UV and transmit the light. That's what sunscreens do.

Ozone actually absorbs UV; if you could see UV, the sky would have a color (just as, say, wine has a color) because the UV light is missing from the region of the ozone absorbtion band. The atmosphere actually scatters red light differentially, as a result of a weird effect called Rayleigh scattering, so the sky looks slightly blue.