Different bands work well in different surroundings. Summoning i often crack open in the summer, and take a walk through the countryside, because its more positive. They are suitable for open surroundings and big hilly landscapes. Burzum is great for woodlands during the winter, i often take a wander at night with a Burzum album, or on a cold day in some woodlands. Darkthrone are great for the night as well. Immortal, as has already been said, should only be played at the top of a mountain in the rain or snow.
All of this appears to be an enlightenning experience that we all go through, listenning to and associating this music with nature helps to further the appreciation of it. It is a spiritual journey, but not in the Christian sense, its more about discovering the ancient spirit within after being brought up in the modern world.