What is convection?

Convection refers to the process of heat transfer that occurs in fluids—liquids and gases—due to the movement of the fluid itself, driven by temperature differences. When a fluid is heated, it becomes less dense and rises; meanwhile, cooler, denser fluid sinks. This movement creates a circulation pattern that effectively transfers heat throughout the fluid.

In the context of how convection operates, consider a pot of water being heated on a stove. The water at the bottom heats up, becomes less dense, and rises to the surface, while the cooler water at the top sinks down to replace it, leading to a continuous motion that distributes heat evenly throughout the pot.

This concept of movement is fundamental to understanding convection as it directly relates to the movement of thermal energy in fluids, distinguishing it from conduction, which is heat transfer through direct contact without fluid motion.