Heat from inside the Earth is called geothermal heat.
Heat from below the earth's surface is called Geothermal Heat.
troposphere
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Geothermal is heat energy obtained from below the earths surface. Once the infrastructure is setup to obtain this energy and convert it for use as heat or electrical energy, getting the energy is practically free.
It's called the convection current.
it flows because if convection currents
I would call this convection currents in the mantle.
Convection.
troposphere
pressure from the heat under the earths surface
Earth's surface is free to radiate heat into space. The interior is not. The interior does transfer heat the the surface, but rather slowly. It is hot due to residual heat from Earth's formation and from the heat generated by the decay of radioactive elements.
Most of this energy is released during the decay of radioactive isotopes. To a lesser extent, this is residual heat, from the formation of Earth - gradually released as Earth's interior solidifies.
Beneath the surface of the earth temperature remains the same. Within the Earth, irregular convection cells within the mantle transfer heat from the core to the surface of the planet. Volcanoes and earthquakes are two examples of heat transferring from the interior to the surface.
Heat from the sun
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radiation & gravity
the answer is radiation
Convection, radiation, and conduction