What does convection refer to?

Convection is defined as the transfer of thermal energy by the movement of fluids, which includes liquids and gases. This process occurs when warmer, less dense fluid rises while cooler, denser fluid sinks, creating a circulating pattern that transfers heat throughout the entire volume of the fluid.

In practical terms, convection is what happens when you boil water: the water at the bottom of the pot heats up, becomes less dense, and rises, while the cooler water moves down to take its place. This continual movement allows for the efficient transfer of heat throughout the substance.

Other forms of thermal energy transfer include conduction, which is the direct transfer of heat through solid objects via molecular collisions, and radiation, which involves the transfer of heat through electromagnetic waves without needing a medium. Hence, convection specifically relates to the dynamics of fluid movement and is a unique mechanism distinct from these other forms of heat transfer.