Tremendous heat and pressure within the earth cause the hot magma to flow in convection currents. These currents cause the movement of the tectonic plates that make up the earth's crust. Lighter (less dense), warm material rises while heavier (more dense) cool material sinks. It is this movement that creates circulation patterns known as convection currents in the atmosphere, in water, and in the mantle of Earth. In the atmosphere, as air warms it rises, allowing cooler air to flow in underneath. Convection currents are heat-driven cycles that occur in the air, ocean, and mantle. They are caused by a difference in temperature, often due to a differing proximity to a heat source. The difference in temperature relates directly to the density of the material, causing this effect. The mantle's convective motions break the lithosphere into plates and move them around the surface of the planet. These plates may move away from, move by, or collide with each other. This process forms ocean basins, shifts continents, and pushes up mountains. Convection is the transfer of thermal energy by particles moving through a fluid. Thermal energy is always transferred from an area with a higher temperature to an area with a lower temperature. Moving particles transfer thermal energy through a fluid by forming convection currents.Energy is transferred in the atmosphere, ocean, and Earth's interior system by three processes: convection, conduction, and radiation. These processes can all occur at the same time on either a small or large scale. There is also a strong coupling found between the atmosphere and ocean. Convection currents are heat-driven cycles that occur in the air, ocean, and mantle. They are caused by a difference in temperature, often due to a differing proximity to a heat source. The difference in temperature relates directly to the density of the material, causing this effect.