Today’s Wonder of the Day was inspired by Sophie from Westchester County, NY. Sophie Wonders, “Why does colder air feel “crisp”” Thanks for WONDERing with us, Sophie!

Do you have a favorite season? Many kids might say summer because of summer break! We love playing in the sun and eating ice cream to cool us down. However, summer air can be unpleasant. Humidity makes the air feel heavy and damp. Some people prefer the cold air of autumn or winter!

Many describe cold air as "crisp," but what does that mean? When we say the weather is crisp, we mean it is clear, clean, and dry. Many people find crisp, cold air energizing and refreshing!

What makes cold air feel crisp? There are plenty of explanations. For one thing, cold air is drier than warm air. As air cools, water is less likely to turn into water vapor. Have you ever watched a pot of water boil? If you have, you know the heat causes water vapor to rise into the air. Summer heat causes more water vapor, which is why it feels so humid. When the weather is cold, the air feels dry because of the lack of water vapor!

We also think cold air is crisp because it's actually cleaner than warm air. When temperatures chill, layers of the atmosphere are more likely to mix. This reduces pollution, making the air cleaner and easier to breathe. That's why breathing cold air feels healthier for many people.

Have you ever noticed that cold air also smells better than warm air? There are two reasons for this. First, odor molecules move much slower in cold weather. That means that fewer smells make it to our noses. Second, we're not as good at smelling when it's cold out. Our smell sensors hide deeper in our noses during cold weather to protect themselves, so fewer smells get to them. That's why cold air smells fresh!

Doesn't the first cool day following a hot summer feel great? There's a reason for that! Our brains have a special region called a hypothalamus. It's like a thermostat for our bodies. When we experience heat or cold, the hypothalamus starts body processes that help us maintain our body temperature. That's what causes us to sweat in the summer and shiver in the winter! Over time, the hypothalamus adapts to long periods of heat or cold. During the summer, our bodies get used to dealing with heat. They work hard all summer long to store water and keep us cool. That's why the first hint of colder weather is so refreshing!

Colder weather doesn't just feel crisp--it also has several benefits for our bodies! Besides being cleaner, cold air helps us think more clearly. Studies show that when it's cold out, people are better at solving problems. Cold also makes us sleep better! Many sleep scientists even recommend sleeping with a fan or in a cold room when the weather is warm.

However, cold air can also be dangerous. While crisp weather can be healthier for many people, those with asthma need to be careful. Cold weather can sometimes cause them to have trouble breathing. Additionally, we all need to remember to bundle up when temperatures drop! Exposure to extreme cold can pose very serious health risks, including frostbite and hypothermia!

Do you prefer cool temperatures, or do you enjoy the summer heat? There are benefits to all four seasons. How might your hypothalamus respond differently to temperatures during spring? What does it do to keep you warm during winter? The next time you take a walk or play outside on an autumn day, think about why the cold air feels so crisp!

Wonder What's Next?

Join us on a trip to the market for tomorrow’s Wonder of the Day!