Convection

What is convection?

Convection is the transfer of thermal energy by means of currents in a fluid (liquids or gases). to put it simply, convection is the transfer of heat by the actual movement of the warmed matter in currents.

Convection current is caused by the change in density. Suppose we consider heating up a local region of air. As this air heats, the molecules spread out, causing this region to become less dense than the surrounding, unheated air. Being less dense than the surrounding cooler air, the hot air will subsequently rise, while the cooler air will sink because they are denser.

Convection currents can only occur in fluids such as liquids and gases but not in solids. This is because convection involves the bulk movement of the fluids which carry thermal energy with them.