Loss of heat to passing air is an example of which heat transfer mechanism?

• A. Conduction
• B. Radiation
• C. Evaporation
• D. Convection

Answer: (D)

Convection is the transfer of heat by a moving fluid. When air passes over the skin, it takes heat away with it as it moves, so the warm air near the surface is continually replaced by cooler air. This flow carries energy away and cools the body more effectively than still air. This is different from conduction, which requires direct contact with a solid; radiation, which transfers heat as electromagnetic waves without needing a medium; and evaporation, which involves a liquid turning to vapor. In real life, even a light breeze can increase heat loss because it enhances convective heat transfer by removing the warmed air more rapidly.