Convection

It is mode of heat transfer in which heat is transferred from one area in a liquid or gas to another area of it as a result of the movement of the molecules of the heated liquid or gas.

This means that convection takes place in liquids and gases. Due to the fact that liquids and gases move around freely, convection results in creating a cycle in which heated molecules move away from the source of heat to be replaced by colder molecules.

This happens because colder molecules are denser than hotter molecules since their molecules are closer to each other.

This makes them heavier so that they sink to the bottom to displace the hotter molecules which rise to the top. When the colder molecules become hot, they are also moved up by the heavy cold molecules.

These cycles continues until a state of equal hotness or equilibrium is achieved throughout the liquid or gas.

A typical example of convection in our everyday life is how water becomes uniformly heated in a cooking pot placed on fire. Convection is the principle behind how air conditioners and refrigerators function.

Moreover, warm air escape from a hot room through its windows and is replaced by cool air from outside by process of convection.