Convection and the mantle

Convection currents

A convection current is the flow that transfers heat within a fluid. Heating and cooling of the fluid, changes in the fluids density, and the force of gravity combine to set convection currents in action.

Convection

Another way heat can be transferred is by the movement of fluids-liquids and gases. Convection is heat transfer the movement of currents within a fluid. During convection, heated particles of fluid begin to flow.

Conduction

Heat transfer between a material(s) is touching is called conduction. For example, a spoon in a pot of soup heats up because the soup is hot. When the particles in the bottom of the pot heat up they vibrate and bump into other particles which then heat, soon the entire spoon heats up. This is responsible for some of the heat transfer inside Earth.

Density and convection

Heat transfer by convection is caused by different temperatures and density within a fluid. Density is a measure of how much mass there is in a volume of substance. For example, a rock has more density then water because a given volume of rock has more mass than the same volume of water.

Convection in the mantle

In earths mantle large amounts of heat are transferred by convection currents. Heat from the core and mantle causes convection currents in the mantle. Convection currents have been moving in earth for over 4 billion years.

Radiation

The transfer of energy through a space is called radiation. Heat transfer by radiation takes place with no direct contact between the heat source and the object. For example, sunlight is radiation that warms earths surface. Heat around a fire is another type of radiation.

Heat transfer

There are three types of heat transfer: radiation, conduction, and convection

How convection currents work

Warm less dense fluid rises up over the cooler fluid, which then sinks down heats up and rises over the fluid on top which then sinks down. This process keeps repeating.

speed of convection

When the liquid or gas is heated it moves faster and spread apart, therefore occupying more space. Then the density decreases. however when the fluid cools, it moves more slowly and settle more closely and the density increases.

Convection in the outer core

there also convection currents in the outer core, these convection currents create earths magnetic field.