Why Wear a Coat?

How come a coat makes me warm?
- Cathy (age 6)
Leal School, Urbana

Heat flows from you out into the air. That means that the molecules you're made of are jiggling around a lot (that means they're hot)  and when cooler air molecules bump into your skin, they get sped up and leave your skin a little cooler. We say that energy is flowing from you into the air. The reason you don't cool down too much is that there's new heat energy flowing into you from a sort of slow chemical burning of your food. If it's cold out, the heat flows out of you faster, maybe faster than you can replace it, so you can cool down. The chemistry in your body is tuned to work best at your regular body temperature, so it's not good to cool down too much. You want that heat from burning food to be able to flow out, so you don't heat up, but not flow out too quickly. A coat helps slow down the flow of heat out to the air, so it helps on cold days.

(published on 10/22/2007)