Radiation of Heat by Bodies
Human bodies, like all objects, radiate heat through a process known as thermal radiation. This is how it works:
What is Thermal Radiation?
- Thermal radiation is the energy emitted by all matter due to their temperature.
- It's a form of electromagnetic radiation, primarily in the infrared spectrum.
How Does it Occur?
- Temperature Influence: The higher the temperature of an object, the more heat energy it radiates.
- Molecular Movement: Atoms and molecules in a body move faster as temperature increases, causing them to emit energy.

Key Mechanisms of Radiation
- Blackbody Radiation: An idealized physical body that absorbs all incident radiation and re-emits it perfectly. Real objects approximate this behavior.
- Stefan-Boltzmann Law: The total energy radiated per unit surface area is proportional to the fourth power of its absolute temperature (T^4). This means a small increase in temperature leads to a significant increase in radiated heat.
Factors Affecting Heat Radiation
- Surface Properties: Dark, matte surfaces radiate heat better than shiny or light-colored surfaces.
- Surface Area: Larger surfaces can radiate more heat compared to smaller surfaces.
Conclusion
- All bodies, regardless of their state (solid, liquid, gas), radiate heat as long as their temperature is above absolute zero.
- Understanding this principle is crucial in fields like thermodynamics, climate science, and engineering.