It's a beautiful day and you're inside. Then you may wonder:can you also tan if you sit inside by the window?
Answer: Yes, you can, if you sit long enough. The radiation from the sun has different wavelengths between 100 and 4000 ngström*. You mainly get a tanned tan from UV radiation between 2900 and 3050 ngström.
Are you protected behind glass?
Ordinary glass does not transmit rays below 3000 ngström. So you are well protected from the sun behind glass, but not completely. If you are behind glass, you can indeed tan or burn.
* An ngström is 1/10 of a billionth of a meter
