What is thermal radiation?

Thermal radiation is defined as the emission of electromagnetic waves due to an object's temperature. All objects emit thermal radiation as a function of their temperature, primarily in the infrared region of the electromagnetic spectrum, although hotter objects can emit visible light as well. This process occurs because the thermal energy of an object causes its particles to vibrate, generating electromagnetic waves, which carry energy away from the object.

Unlike conduction and convection, which require a medium (solid or fluid) for heat transfer, thermal radiation can occur in a vacuum, allowing for energy transfer between distant bodies, such as the Sun and the Earth. This concept is critical in understanding energy transfer in various environmental and engineering contexts, such as heating, cooling, and thermal management systems.

The focus on electromagnetic waves highlights the fundamental nature of how thermal radiation operates, distinguishing it from other heat transfer mechanisms like conduction, which involves direct contact between materials, and convection, which relies on fluid movement.