Buzz
Does snow have a smell? Your logical brain might argue no: Snow is simply frozen water, so it should be odorless. But if you’ve ever sensed an impending snowstorm from a familiar tickle in your nose, you know the situation isn’t as simple as it seems. So, what exactly occurs when you ‘smell’ a meteorological event? The answer doesn’t lie so much in specific odor molecules, but in the environmental conditions in which they are detected.
In a segment of the now-retired podcast Physics Central, olfactory scientist Pamela Dalton explained the perfect combination of physical conditions that lead to what we perceive as the smell of snow. When temperatures drop near freezing just before a snowfall, it becomes harder to pick up scents in the air compared to milder weather. Cold slows the movement of air molecules, and with less activity, some smells become less intense. In other words, ‘smelling snow’ is partly just about noticing fewer odors outdoors than usual.
However, if it were just that, a snowstorm would smell much like any cold, dry day. What truly differentiates it is humidity. Just before a snowstorm, the air is more humid than usual. This added moisture is what triggers the snowflakes to fall: When the air reaches its maximum moisture capacity, it releases some of that moisture—whether as rain, sleet, or snow—back onto the ground. That humidity also gives your olfactory system a boost, allowing you to smell better. For many, the sensation of being able to smell with a warm, moist nose in freezing weather is associated with the impending snowfall.
While everything around you is changing, there are also processes inside your body that help explain the unmistakable scent of snow. You feel the cold air you breathe through your trigeminal nerve, the same nerve that registers sensations from hot peppers or mint toothpaste (it also interprets other facial sensations, which is why you might sneeze in sunlight). Although this system is separate from your olfactory system, the information it provides is often grouped with traditional scents like coffee or pine.
These factors—cold weather, humidity, and the activation of your trigeminal nerve—work together to produce something that’s not really an odor but a sensory experience that you’ve come to associate with snow. That’s why, when asked to describe the scent, people frequently use words like clean, fresh, and cold—descriptions that don’t have much of a smell themselves.
