The Three Methods of Heat Transfer

There are three methods of heat transfer. However, before we jump into those methods, lets first review just what heat is. Many people often confuse heat and temperature but there is a fundamental difference that should be remembered. Remember that heat is the total kinetic energy of all the moving atoms, ions, or molecules in any given substance. This motion does not account for the actual motion of the object. This is only the random movement of atoms within the object. When you witness a glass of water, you probably will not imagine that all the water molecules are constantly in random motion and the heat stored in this glass is the total kinetic energy of all the molecules. Heat, as we're about to discuss, also refers to the transfer of energy between two objects at two temperatures. Let's sidetrack for a second and discuss temperature. It is defined as the average speed of motion of all the atoms, molecules, etc. in a given object. This makes sense because as the temperature increases, so does the average speed of all the little building blocks.
The first method of heat transfer is known as convection. Let's take an example of a pot on a stove filled with water. When the stove is turned on, the heat vaporizes the water at the bottom. Because the water in gaseous form is less dense than the surrounding water, it rises. Water at the top that is cooler then falls to replace the vapor moving up. This movement is known as convection and it is the first method of heat transfer.
The second method is called conduction. This is heat transfer through direct contact. The heat from the stove causes the molecules in the pot to vibrate faster. Remember this means an increase in temperature. This vibration spreads throughout the pot and eventually will burn you if touched.
The last method is radiation. The pot gives off energy in the form of radiation. Even though air is a poor conductor of heat, infrared radiation will be able to travel through it. All of heat transfer can be understood by these tree methods, that is, heat transfer will fall into one or more of these categories.