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Why Does Cold Air Smell Different?

Why Does Cold Air Smell Different?


It’s winter. You can feel it. You can see it. You can smell it? You can, and we’re not talking about winter’s chimney smoke, pine needles or chestnuts. We’re talking about the cool, crisp smell of winter’s air. We explain this chilly scent with help from Discovery News.


Our explanation is two-fold: physical and psychological.


The physical reason a cold day smells different than a hot one is that there are simply fewer smells to smell, and our noses aren’t as sensitive to smells in the winter. Pamela Dalton, an olfactory scientist at the Monell Chemical Senses Center in Philadelphia, explains to Discovery News that this can attributed to odor molecules moving more slowly when temperatures drop.


Let’s use your dinner leftovers as an example. Next time you pull a meal out of the refrigerator or freezer, take a whiff. How strong is the scent? Now heat up your food and smell again. Is the scent stronger than before? This change in smell is because as you heated up your leftovers, those odor molecules began to speed up.   


But these moving molecules aren’t the only things determining what we can and can’t smell. The other factor is our nose, of course. Dalton explains to Discovery News that as a protective response against cold, dry air, the olfactory receptors that lie inside all of our noses bury down in the winter.


So the lack of smells plus the lesser ability to smell makes winter have a different odor than summer.


The psychological reason a cold day smells different than a hot one is that we have come expect it to smell a certain way.


"What you think a smell will be impacts whether you like it and what you perceive it to be," Alan Hirsch, a neurologist and psychiatrist in Chicago, told Discovery News. "So, if you go outside in the winter and you are used to smelling snow or chestnuts in the fire or whatever you happen to smell outside, that's what you will interpret smells to be."


Now stand outside and take a deep breath in through your nose … it smells like winter, doesn’t it?


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