The most beautiful part of reading some novels, especially historical fiction, is that feeling of being able to partake of moments that you could never be part of. One way that writers do this is using sensory inputs to add to the overall atmosphere in the story. So what the characters see, hear, touch, taste and smell constitute the setting of the novel. Morgen Witzel writes brilliantly about using smell as a tool to recreate a more realistic setting. Proust is famous for having used smells to evoke memories. Pleasant smells like attar evoke the Orient and the odious smell of the battlefield, replete with ordure and gunsmoke add to the reality of the scene. In fact, smell and taste can transport you through time as a novel does. Seems worth giving this tip a try.
As well as evoking memories, one can use smells to alter the psychological mood of a scene. The kind of smell and the way it is described will invoke different unconscious memories. Weather can do the same thing: bright sunshine tends to sway people towards hope and optimism, while rain and thunder evoke a more gloomy mood. And, of course, weather has its own smells: the baking smell of hot stones or the sweet resin of pine trees in sunshine, the earthy reek that follows fresh rain, the tang of iron in the wind that tells you it is about to snow.
Read Smelling History: Evoking a sense of the past through its smells by Morgen Witzel.