Earth structure and materials Convection and the mantle

Transfer of heat Heat is constantly being transferred inside and around our Earth’s surface Heat transfers from: Remember: heat makes the atoms and particles in an object move faster, producing energy The movement of energy, from warmer objects to cooler objects is called Heat Transfer Three types of heat transfer: Radiation Convection Conduction Warmer objects Cooler Objects

Transfer of heat The sun constantly transfers light and heat through the air, warming your skin. The transfer of energy that is carried in rays like light is called radiation. Heat is transferred between materials or objects that are touching, called conduction. The sand transfers its heat to your skin when walking along the beach. Seagulls often soar on warm air currents. The currents are created as warm air rises from the ground. The warm air heats cooler air above it. Heat transfer by the movement of fluid is called convection.

Name the type of heat transfer

Convection in the earth’s mantle When heating up a liquid, like soup for example, the liquid from the bottom gets hot, expands the pot and rises to the surface. As the liquid expands, the liquid becomes less dense. Density = measure of how much mass there is in a given volume of substance The less dense liquid at the bottom moves upward and floats to the cooler surface, the warm liquid cools and becomes more denser. Gravity then pulls the colder liquid back down to the bottom, which continues the cycle of it being reheated and rising again The flow that transfers heat within the liquid is called Convection - Three processes or forces combine to set convection motion: Fluid’s density Heating and cooling of fluid Force of gravity

Convection in the earth’s mantle Most rock is more dense than water because a given volume of rock has more mass than the same volume of water