Why Is Marble Cold?

Temperature

• Unless it's a really, really hot day, your body is nearly always at a warmer temperature than your surroundings. That's because your body spends considerable energy to keep things that way. Like other warm-blooded or homeothermic animals, you maintain a constant internal temperature of about 98.6 degrees F. It follows from the second law of thermodynamics that heat always flows from hot objects to cold objects, and never the other way around. When you come in contact with a surface like wood, carpet, marble or metal, you lose energy to the surface in the form of heat.

Conductivity

• The rate at which heat is transferred through a solid is called its thermal conductivity. Some substances like metals have high thermal conductivities, so they can act as conduits for heat. Other objects like wool blankets have low thermal conductivities and transfer heat inefficiently. Marble is nowhere near as good a conductor as most metals, but its thermal conductivity is 10 to 20 times greater than that of most woods, and much better than the nylon fibers in your carpet.

Rate of Heat Transfer

• When you say something feels cold or hot, what you're actually experiencing is the direction of heat transfer to or from your skin. When your skin loses heat to an object, you feel that the object is cold. Marble is a much better conductor than wood or carpet, so it conducts heat away from your skin much more rapidly, and the marble feels fairly cold to you. You'll find that much the same is true of metal; if you grasp a metal object on a cold day, you'll find it's uncomfortable to hold it for long.

Specific Heat

• Another factor to consider is the specific heat, the amount of heat it takes to raise the temperature of an object by a degree. Wood actually has a much higher specific heat than metal and marble. Consequently, it would take less heat energy to raise marble to the temperature of your hand. The marble will never approach your hand's temperature, however, because unlike the wood, it dissipates heat relatively quickly through conduction.