A convection current is a process that involves the movement of energy from one place to another. It is a type of fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity. Convection currents transfer heat from one place to another by mass motion of a fluid such as water, air, or molten rock. The process of convection only happens in fluids, i.e. in liquids and gases, because molecules within them are free to move. Convection currents tend to move fluid or gas particles from one place to another, and they are created as a result of the differences occurring within the densities and temperature of a specific gas or fluid. The key principle behind convection currents is that warm fluid rises and cool fluid sinks. Convection currents can happen with any non-solid substance, and they can cause plate tectonics, thunderstorms, desert and tropical regions, and even the Earths magnetic field. The mantle within the Earths surface flows due to convection currents, which are mainly caused by a very hot material present in the deepest part of the mantle, which rises upwards, then cools, sinks, again and again, repeating the same process of heating and rising.