Thermal energy has no known definition and the term cannot be really found in a dictionary of physics or science. Mostly, it is thought of as being a synonym for thermodynamic energy or a synonym for heat. It can however, have two components which are internal potential energy as well as internal kinetic energy.

The internal potential energy is the systems energy contained at a given moment of time which is dependent on the relative placement of all of its constituent parts. On the other hand, the internal kinetic energy is the systems energy contained at a given moment in time governed by the relative motion inside the system of all the constituent parts of the system.

Internal Energy Of The System

Thermal energy is the internal energy of the system that is in thermodynamic equilibrium because of its temperature. In a hot body, this form of energy is greater than for a similar cold body. However, cold water contained in a large tub could have more thermal energy than a cup of boiling water. Transferring this form of energy from one body that is the hotter of the two is possible to the second body, that in most cases is colder.

In military usage, the term thermal energy is the energy coming out from the fireball in the form of thermal radiation. Every bit of thermal energy received per unit area at a select distance from the nuclear explosion will be described in calories per square centimeter.

Within a system, there can be constant interchange of internal potential energy as well as internal kinetic energy. However, the sum of these two energies referred to as thermal energy in a thermodynamically isolated system will remain constant. For ideal gas, the thermal energy is the total of the kinetic energies of the particles that are ideal, as well as those without volume, and which interact with the containers walls and not with each other.

Some noted experts on the subject even think of it as being heat when thermal energy is used as a noun. To describe solar energy, one will need to realize that it is of two types thermal energy and electric energy. You can get thermal energy everywhere and it is what will provide light in the day, and is always heating the earth, the human body as well as in our homes. All of this is also readily available to mankind free of cost.