What is convection primarily responsible for in heat transfer?

Convection is primarily responsible for the movement or circulation of fluids, which includes liquids and gases. In convection, heat is transferred through the motion of these fluids. As a fluid is heated, it becomes less dense and rises, while cooler, denser fluid sinks. This creates a continuous cycle of movement that facilitates heat transfer. For example, in a pot of boiling water, the heat from the stove warms the water at the bottom, causing it to rise and be replaced by cooler water from above. This process effectively distributes heat throughout the fluid.

The other options pertain to different modes of heat transfer: radiation refers to the transfer of heat through electromagnetic waves, which can occur in a vacuum; conduction involves heat transfer through direct contact between solids; and absorption relates to how solids can take in heat energy. While all these are important concepts in thermodynamics, they do not specifically define the role of convection in heat transfer.