earth's interior heat is the engine that powers the external combustion engine.
earth's interior heat is the engine that powers the external combustion engine.
earth's interior heat is the engine that powers?
external combustion engine
earth's internal heat powers most geological processes and drives plate tectonics. despite its geological significance, this heat energy coming from earth's interior is actually only 0.03% of earth's total energy budget at the surface, which is dominated by 173,000 tw of incoming solar radiation. the insolation that eventually, after reflection, reaches the surface penetrates only several tens of centimeters on the daily cycle and only several tens of meters on the annual cycle. this renders solar radiation minimally relevant for internal processes.









































section::::heat and early estimate of earth's age.
earth's internal heat budget
external sources of planetary heat (namely, radiation from a planet's host star) can have drastic effects on geodynamic regime. with all other variables held constant, an earth-sized exoplanet with a surface temperature of 273 k will evolve over its geological lifetime from a plate tectonic regime, to episodic periods of plate tectonics interspersed with stagnant lid geodynamics, to a terminal stagnant lid phase as interior heat is exhausted. meanwhile, a “hot” planet (759 k surface temperature) under the same initial conditions will have an amorphous surface (due to lithospheric yield stress being constantly exceeded) to a stagnant lid as interior heat is exhausted, with no plate tectonics observed.
geodynamics of terrestrial exoplanets