system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do people smell different when they've been outside in the cold?

I've noticed that during winter/autumn months, when people go outside into colder weather, they tend to carry a distinctive smell when they return. You can smell it on their clothes, particularly on coats, but it does fade quickly. What is it?
gpt
because most of the things we smell are volatile substances (evaporate easily). 

however when these substances get cold they have more difficulty evaporating.   so the person who has been in the cold made their jacket cold and so they stop emitting their normal smell.  and any smells in the air condense on the jacket.  like the water condenses on the cold toilet. so smelling them only smells the smells that evaporate in the cold.  

then after they have been inside and warm up the compounds can start evaporating easily again and their smell returns to normal.