Before I talk about the heat budget, let's be sure we understand the definition of heat.
Heat is a form of energy arising from the random motion of molecules.
Those molecules may be air, water, stone or any other form of matter. We measure the heat of a material by taking its temperature, but heat and temperature are not the same thing. As you cool a substance, you remove energy and its molecules move more slowly. Think about your body when you've been out carving up the slopes all day or when you've been diving in the cold Pacific all day. Your fingers and everything else are hard to move.