What is radiation in terms of heat transfer?

Radiation in terms of heat transfer refers to the mechanism by which heat is transferred in the form of electromagnetic waves, specifically heat rays. Unlike conduction or convection, which involve physical contact or movement of a fluid medium, radiation can occur even through a vacuum. This means that heat can be transferred from one object to another without the need for a physical medium to facilitate the transfer.

For example, the warmth one feels from sunlight is due to radiation; the sun emits heat rays that travel through space and warm the Earth. This understanding of radiation is crucial in effective heat management in refrigeration systems and in evaluating how different surfaces absorb or emit heat in various temperature conditions.