As I arrive home in the evening, its getting darker and darker each day. It amazes me how our son continues to learn words and understand mother nature. Just the other day, he pointed outside and said "dark...see dark." So we went outside and he continued to say "Ohhh...dark..." He then pointed at the sky and said "stars." Not sure who taught him the word or visual of stars (not me or my wife), but it was a great moment.
So, many evenings we go outside prior to going to bed and feel the cool air, stare at the stars and say "night sky."
I really think by doing such simple activities, he will have a better feel for his surroundings and appreciate the many beauties of the outdoors.