Each season has its own distinctive scent. What does spring smell like, and what does autumn smell like? Fresh pumpkin pie and lilacs? People not only perceive the changes of the seasons, they also sense them.
What exactly is that familiar scent that hits us in early spring? The sweetness of blooming flowers and trees? Or perhaps refreshing herbs and the first warm evenings? Whatever it is, it's more complicated than it might seem.
Smell chemistry and human perception
The most familiar scents are a blend of many different aromatic molecules. For example, the scent
of a rose is composed of hundreds of volatile chemical compounds. The scent we experience after rain, on the other hand, consists primarily of ozone, geosmin (a chemical released by soil bacteria), and plant oils. The chemistry of aromas is complex enough on its own, but humans make it even more complex. This is because the perception of scents is influenced by other senses, beyond smell. Smell is a collection of what we see, hear, and feel, emotionally and physically. For example, your grandmother's scent is likely a "mixture" of her favorite perfume, the cakes she bakes, as well as auditory and visual elements that trigger memories of her.
The relationship between temperature and smell
So what causes our
noses to detect the scent of spring each year? This olfactory perception is based on a multitude of factors. One of the main factors is temperature. The warmer and more humid the air, the more and faster aromatic molecules circulate. This is why a hot pile of garbage smells worse, and cookies fresh out of the oven are more aromatic. On frosty, crisp days, the array of scents is poorer. The city smells less intense when the temperature and humidity drop.
The psychological basis of seasonal scents
Our expectations regarding scents have a profound impact on how we actually smell. If someone is accustomed to winter smelling like snow, wood in the fireplace, or something else, they will interpret the scent of winter that way. Our relationship to seasonal scents is determined not only by associations but also by where we live and how we live. Tradition and customs shape our experience of the world; for example, the foods and drinks we associate with spring are fragments of its scent.
Another season – a different set of scents
The collection of odors in the air changes with the changing seasons. If you live in a city, your summer likely smells of gasoline, beer from beer gardens, or grilled food. As soon as the temperature drops, these odors become less pungent, and autumn's aromas—decaying leaves or rotting fruit—take over.
