Its always funny to me what sensory stimuli will trigger memories or feelings.
I was going to make cookies today (actually, I wanted to make cinnamon rolls, but since I literally have only about 14 inches of counter space--between my fridge and microwave, with the stove right behind me--I am against bread making while living in this house), but I had to run to the store for a few things first. Its quite rainy and coldish (which is why I wanted to make cinnamon rolls), and as I was unloading the girls from the van, there was a pretty strong diesel smell in the air. The combination of the chilly rain and the smell of diesel made me feel homesick. I didn't know what to make of that one--I honestly don't know why that combination evokes such a feeling in me. My mom and dad were raised by loggers, but I wasn't.
Over the years, I've realized several smells/combinations that have an instant effect that way. If I'm out in the fresh air and sunshine, especially if I'm sitting on the grass barefoot, a whiff of cigarette smoke will make me instantly feel at home. The smell of grass fire, just about anywhere, triggers all kinds of happy memories. The smell of slightly damp leaves and wet soil always makes me start daydreaming about playing at my grandma's house as a small child (her yard was completely bounded by leafy trees, next to a creek).
And--probably my favorite--being in the mountains, surrounded by the smell and sight of conifer trees and good, clean mountain dirt, puts me instantly at ease, no matter the circumstances, especially if there's a slight breeze. A light rain, even if I'm camping, just makes it even more relaxing for me (downpours are another issue, however). Its what I imagine coastal-dwellers feel at the beach, from having listened to many of them talk about it. I guess that, even though I developed a tremendous love for the beach in the nearly 10 years that I lived at or near the ocean, my heart never really belonged to it. The mountains still have a much stronger pull on me.