If you're based in Dublin there's no need to stick within the borders of a large city and not see any nature. Just a half hour drive from Dublin you'll find the Wicklow Mountains.
This area is absolutely stunning with its mountains, lakes, waterfalls and of course a zillion sheep :-)
It's hard to believe that a city like Dublin is so nearby.
I went to Wicklow in the winter; in January of 1999 to be precise, and was lucky enough to enjoy one of those extremely bright and sunny winter days. In the pictures below you can see more of Wicklow Mountains.