ELI5: Why do hot things smell stronger than cold things?

Hot things smell stronger because heat gives tiny scent particles more energy to fly into the air and reach your nose faster.

Everything you smell is made of tiny, invisible floating pieces called molecules. When something is cold, these little pieces are tired and move very slowly, mostly staying stuck to the object. But when you heat something up, it gives those pieces a huge burst of energy.

Think of it like a room full of sleeping puppies versus a room full of excited puppies:

• When it is cold, the scent pieces act like sleepy puppies napping in a pile; they do not move around much, so you have to walk right up to them to notice them.
• When it is hot, it is like the puppies just woke up and started zooming all around the room; the scent pieces bounce into the air and spread out in every direction.

You can easily see this in your everyday life:

• Cookies: A tray of cold cookie dough in the fridge barely has any smell at all, but as soon as the cookies bake in the hot oven, the whole house fills with a delicious, sweet aroma.
• Pizza: A slice of leftover pizza from the refrigerator does not smell very strong until you warm it up in the microwave. Once it gets hot and bubbly, the smell hits you immediately.
• Trash: A garbage can does not smell nearly as bad in the freezing winter, but on a scorching hot summer day, the heat makes it smell terrible from down the street.