it is now reinforced by the ties between your close group of friends.
Explanation:
If a person who was formerly an acquaintance becomes closer with your group friends, it is likely that you will end up become friends with that person, or at least, that you and that person will meet more often and perhaps get to know each other better.
This is because your close group of friends will start briging the former acquaintance to the new interactions.
Well it would depend how cold it would be, but I would say if it's below freezing cold, personally (when I go skiing actually) I would dress up in an under layer thing (I don't really know what you call it), a fleece sweater, (assuming there's snow) snow pants, and a jacket.
If you're climbing Mt. Everest, that's a whole different story.