How do convection currents work in the mantle?
law of thermodynamics, must flow to a cooler place, and subsequently rises to the surface of the Earth. If the Earth were smaller, this heat would flow by conduction, but because of the relatively large size of the Earth, convection also takes place. Thus, as in heating a pot of water on a stove, convection currents are established within the earth, which bring warm material to the surface and send cooler material to the interior.
