Hot Pie On A Cold Day

On last week’s episode, we tried to tackle one of our listener-submitted questions about cold and winter. Specifically:

Why does hot food smell so good as the odors waft out windows on a cold crisp winter day?  Does the cold change the smells to make them stronger?

We didn’t have time to answer this one on the air, but we understand the burning desire for knowledge only quenched by evidence-based scientific data, and we didn’t want to leave you hanging. So here’s what we found:


Actually, it probably has more to do with how your brain perceives these smells than it does with the cold day having any affect on those smells.

When you get a whiff of garlic, what you’re smelling are these sulfur-based molecules in the garlic that evaporate into the air at very low temperatures. We call them volatile organic compounds, because they go from being a solid to being a vapor with very little impetus. This is why you can smell garlic that’s just sitting on your counter.

As the temperature of the air drops outside, these volatile organic compounds known as odors, slow down, and there are generally less of them floating about in the ambient air.  So there just isn’t as much to smell out there in winter, and what is out there isn’t nearly as potent.

Increasing heat increases the chance of the molecules escaping into the air, so as you say, cook the garlic, the odor increases. The hotter the air, the faster and farther the odor molecules can travel.  Additionally, increasing humidity traps these odor molecules and allows them to linger.

To help explain this better, imagine conditions opposite to what it’s like outside right now: a hot humid summer day. Ah, the lovely smell of an overflowing garbage can in the park on this staunchy afternoon. It’s pretty gross isn’t it? And powerful. That’s because odors intensify as the heat increases and as the humidity goes up, and conversely lose their intensity as the air gets cooler and drier.  

Our sense of smell dulls in the cold as well. Neurons called olfactory receptors line your nasal cavity, and are coated in a layer of mucus. Millions and millions of them. Each receptor is tuned to a specific odor molecule. So say, when a molecule of coffee wafts up to your nose, it binds to an olfactory receptor specific to receive and identify it.

The binding triggers the olfactory receptors to send electrical signals that are passed along to the brain, letting you know a sweet sweet hit of caffeine is nearby. When exposed to cold air, these olfactory receptors apparently “bury themselves” a little deeper, and become less sensitive.
So if food smells stronger and better in the winter, you’re probably just perceiving the smell of hot food to be more intense.  Since there are generally less odors just floating around in the winter to get in the way, wouldn’t the odor of the food just sort of…. stands out more.


If YOU have a scientific question you’d like us to answer, please email it to: 

21. Snowflakes

A raging ice storm has had most everyone in Portland trapped indoors, with nothing to do but listen to old episodes of Everything Is Interesting.  Visions of snowflakes dancing in their heads, K+K the science questions they dreamed up about cold weather, and the way snow forms.

They also asked listeners what snow questions they had been pondering, and got some pretty good ones! So here’s the answers!

20. Hi Honey, I’m Living In the Future!

When the future is now, what will you be coming home to? On this episode, K+K take a look at how our houses will change as we begin to run out of finite resources like petroleum and natural gas. Refrigerators will be powered by magnets, your clothes will be made from garbage, and your house might just be smarter than you are. Get ready for Crab Pants!

Warning: the future is full of lightning

19. Science Fact or Science Fiction?

Continue reading 19. Science Fact or Science Fiction?

18. Santius Clausadae

If you’re an avid pursuer of rare and unique species, this is a very exciting time for you. Christmas Eve is when you have the best chance of catching a glimpse of the elusive Santius Clausadae, more commonly known as the Santa Claus.

How he makes toys with those flippers is anyone’s guess.

Unfortunately, researchers have yet to successfully acquire DNA samples from this creature. We’re instead forced to speculate on how the Clausadae species looks and behaves in order to survive in it’s natural habitat: the arctic.

17. Bioluminescence

Its December, the world is cold and dark. Luckily the world glows bright with the magic of bioluminescent organisms! Fireflies, squid, mushrooms, and bacteria generate their own light for the purposes of luring prey, attracting mates, and even blending in with their environments. Follow Keera and Kira on a magical journey to discover:

  • What’s special about a bioluminescent animal’s body
  • An exotic Brazilian mushroom that glows in the dark, and how scientists discovered its purpose
  • What happens when scientists inject genes for glowing proteins into traditionally non-glowy organisms

15. Thanksgiving Science

Whats the best way to cook a turkey? Will microwave ovens fry your brain? What is the difference between saturated fats and unsaturated fats, really? And do you know the difference between convection, conduction and radiation?

14. Watson the Water Molecule Becomes A Rain Drop

Join the Science Ladies and Jefferson, the Up-For-Any-Challenge DJ from XRAY in the morning, as they relay a tale sure to delight both young and old.  This is the story of Watson, a water molecule from the Pacific Ocean, and his amazing journey up into a rain cloud, and back down again.

Somewhere in the middle of the story, we stop to quiz the XRAY crew on some very important facts about lightning. You might call it a Lightning Round.

13. Marijuana Part II

Is there research to support that marijuana can be used as medicine? What diseases would it treat?

What is CBD, and what does it do to your body?

12. Marijuana – Part I

Today’s show is Part I of a two-part episode, all about the science of Marijuana! (Don’t worry, we live in Oregon. It’s totally legal.) Today Kira and Keera cover:

  • Human’s millennia old history with marijuana
  • The specifics of the Cannabis species
  • What THC does to your neurons to gets you high
  • Science of drug addiction