I very appreciate the article, it was very good start for me, but someway I actually wanted to know more... :)
Here's a short summary of what I found:
Whenever you need protection (sunscreen, sunglasses) depend on so-called UV Index. UV Index varies during the hours of day (it's much higher during midday) and time of year. You can find actual value at local meteorological office. If the index is greater than 2 during the time of day/year you are outside, you need protection. Except you are near water or snow, which may increase intensity greatly.
I very appreciate the article, it was very good start for me, but someway I actually wanted to know more... :) Here's a short summary of what I found: