What is the process of convection?

Convection is a process that involves the transfer of heat through the movement of fluids, which can include liquids and gases. When a fluid is heated, it can become less dense and rise, while cooler fluid descends to take its place. This creates a circulation pattern that transfers heat throughout the fluid. The movement of air masses, for instance, is a common example of convection in the atmosphere, where warm air rises and cool air moves in to replace it, influencing weather patterns and air temperature distribution.

The other options reflect different modes of heat transfer. Direct contact heat transfer is called conduction, and it involves the transfer of thermal energy through matter, without the movement of the material itself. The process referred to in the third option inaccurately limits convection to liquids only, whereas convection occurs in both liquids and gases. Radiation, on the other hand, involves the transfer of heat through electromagnetic waves without the need for a medium, exemplified by the heat from the sun warming the Earth. Thus, option B accurately characterizes convection as a heat transfer process driven by the movement of air or fluid masses.