In winter, human olfactory receptors take a nap.

Not only do low temperatures keep us indoors in winter, but our sense of smell is less excited about being outdoors in winter because there are fewer scents to smell. According to Pamela Dalton, a scientist at the Monell Chemical Senses Center, a multidisciplinary institute for olfactory and gustatory research in Philadelphia, odor molecules move much slower through the air in winter. This means it's harder to detect a scent. We're not as sensitive to odors in winter because our olfactory receptors are somewhat hidden. This is likely because they protect themselves from the cold and dry air. Smells are some of the most powerful indicators of the seasons. Each season brings its own unique set of aromas, each distinctly different from the other. Fresh flowers and thawed earth in spring, barbecues and hot pavement in summer, rustling leaves in autumn, and finally, snow and pine needles in winter. Some of these scents bring more joy than others. Have you ever noticed how much you crave being outside in spring or summer? Or, conversely, how tightly you cling to the warmth of your homes and apartments as winter stretches on? In winter, we compensate for the lack of scents by appreciating the homely aromas of this season. Whether it's lighting a log in the fireplace, making a delicious soup, or baking cookies, we need to satisfy our senses somehow!