Which method transfers heat in liquids and gases?

Convection is the method that transfers heat in liquids and gases. This process occurs when warmer areas of a liquid or gas rise while cooler, denser areas sink, creating a circulation pattern. As the warmer fluid rises, it carries heat with it, while cooler fluid moves down to replace it, establishing a continuous flow that effectively distributes heat throughout the medium.

Understanding convection is important in respiratory care, especially when considering the heating and humidification of gases in respiratory therapy. For example, in devices like humidifiers and nebulizers, the air or gas is warmed and humidified using convection to ensure that it reaches the lungs at the appropriate temperature and moisture level for therapeutic effectiveness.

In contrast, the other methods mentioned involve different processes: conduction refers to heat transfer through direct contact between materials, radiation involves heat transfer through electromagnetic waves without the need for a medium, and evaporation is a cooling process where liquid transforms into vapor, absorbing heat in the process but not acting as a method of heat transfer within fluids like convection does. Thus, convection is the distinct process that specifically pertains to heating in liquids and gases.