Convection

Have ever you had a hot pot meal in the winter? You may notice that the food keeps moving up and down in the water even when the temperature is well below that of boiling. This indicates that bulk movement of water exists when it is being heated. In fact, this movement of water, known as convection, serves as an effective way of heat transfer, especially when the rate of heating is high.

Convection is the process of heat transfer by the bulk movement of a fluid, i.e., liquids or gases.