Well, if there is sun and snow the light reflected around is tremendous, you literally cannot open you eyes. It is nothing you will see here, at ground level (not sure why, cleaner sky and atmosphere, no dust). If you plan to go anywhere on a high mountain be sure to have black glasses that are guaranteed to block all UV, it is quite serious your your eyes will get hurt if you stay there for a long time.
As a side effect, anything that is dark will absorb all this light and will get quite hot.
It could be 0 degree and I think you will be ok in just a black sweeter.
The other side, if the sun happens to get behind some clouds, you will freeze in minutes.