Materials that keep us warm
Chemistry · Key Stage 1 · The School
Where warmth really comes from
Your body makes its own heat all the time. A jumper does not make heat. It traps the warmth close to your skin. Wool and fleece are good at trapping warm air. That trapped air is why you feel warmer.
Why metal feels cold
Metal does not make cold either. Metal lets heat move away from your hand very fast. That is why a metal door handle feels cold in winter. A wooden handle feels less cold, because wood lets heat move away more slowly.
Trapped air is the trick
A thick, fluffy material traps more air than a thin, flat one. Trapped air is a poor carrier of heat, so it slows the warmth escaping. That is why a fluffy fleece feels warmer than a thin cotton shirt, even though both start at room temperature.
Touching a coin and a jumper
Touch a metal coin and a wool jumper, both left on the same table all night. They are the same temperature. But the coin feels cold, because it moves heat away from your hand fast. The jumper feels warmer, because wool moves heat away slowly. Your hand is not measuring temperature. It is measuring how fast heat is leaving it.
Choosing for a cold day
On a cold day, choose materials that trap air. A fleece jumper, wool socks, and a padded coat all work the same way. Layers trap even more air between them. That is why several thin layers can feel warmer than one thick one.