Thermal vs Heat
The word thermal and heat are used interchangeably by people, as if both refer to the same entity. Of course, terms like heat energy and thermal energy are used to refer the amount of energy that is transferred from an object at a higher temperature to one at a lower temperature until both achieve a state of equilibrium when their temperatures are equal. The word heat is used more to describe hot climatic conditions at a place, while thermal is a word used more to describe conductivity or resistance of an object to change of temperature in the surroundings. Let us take a closer look at the two concepts to find if there are indeed any differences between thermal and heat.
In cold climatic conditions, it is common for people to install heating systems, and we are aware of this invisible entity that gives us a sensation of warmth when we have worn woolen jackets or pullovers. Heat is a form of energy just as sound and light are, and the expression thermal energy differentiates it from light and sound energy.
However, at a more sublime level, there is a difference between thermal and heat. We know that heat is the measure of temperature difference between two bodies, as when we feel it when we accidentally touch a hot iron we are using to iron our clothes. But when we consider a single body, it is thermal energy that a body has, and not heat. The concept of heat comes into the picture only when there is another hotter or colder body in contact with a body.
We refer to sun’s energy as thermal energy and call power plants using fossil fuels to produce electricity as thermal power plants. This thermal energy becomes heat or energy in transit while it is travelling. Once it is absorbed by earth or other objects on earth, such as water bodies or people living on earth, this heat once again becomes kinetic energy. It is a part of the total internal energy of the system, whether we are talking about a person, water body, or even the whole of earth. Thermal energy of the Sun is mainly stored in water bodies on earth.
If you have had a candle light dinner or had to study under a lit candle when electricity was cut, you must have noticed candle generating thermal energy as long as it keeps on burning. This thermal energy, as it moves away from the candle’s surroundings, becomes energy in transit or heat, but as soon as this heat is absorbed by a person sitting in the room, this again becomes thermal energy.
What is the difference between heat and thermal?
• Thermal energy is the total internal energy of a system while heat is energy in transit.
• Thus, heat is the energy being transferred from a hotter body to a colder body in contact until both achieve equilibrium.
• Sun is said to have thermal energy, but it becomes heat or energy in transit when it travels to earth. However, it is again changed into thermal energy when water bodies on earth absorb this heat.