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On Earth, the Rayleigh number for convection within Earth's mantle is estimated to be of order 10 7, which indicates vigorous convection. This value corresponds to whole mantle convection (i.e. convection extending from the Earth's surface to the border with the core). On a global scale, surface expression of this convection is the tectonic ...
Mantle convection is the slow creeping motion of Earth's rocky mantle caused by convection currents carrying heat from the interior of the Earth to the surface. [33] It is one of 3 driving forces that causes tectonic plates to move around the Earth's surface.
Forced convection: when a fluid is forced to flow over the surface by an internal source such as fans, by stirring, and pumps, creating an artificially induced convection current. [3] In many real-life applications (e.g. heat losses at solar central receivers or cooling of photovoltaic panels), natural and forced convection occur at the same ...
Earth heat transport occurs by conduction, mantle convection, hydrothermal convection, and volcanic advection. [15] Earth's internal heat flow to the surface is thought to be 80% due to mantle convection, with the remaining heat mostly originating in the Earth's crust, [16] with about 1% due to volcanic activity, earthquakes, and mountain ...
The volcanism often attributed to deep mantle plumes is alternatively explained by passive extension of the crust, permitting magma to leak to the surface: the plate hypothesis. [24] The convection of the Earth's mantle is a chaotic process (in the sense of fluid dynamics), which is
The pressure at the bottom of the mantle is ≈140 GPa (1.4 Matm). [24] The mantle is composed of silicate rocks richer in iron and magnesium than the overlying crust. [25] Although solid, the mantle's extremely hot silicate material can flow over very long timescales. [26] Convection of the mantle propels the motion of the tectonic plates in the
All convective processes also move heat partly by diffusion, as well. The flow of fluid may be forced by external processes, or sometimes (in gravitational fields) by buoyancy forces caused when thermal energy expands the fluid (for example in a fire plume), thus influencing its own transfer. The latter process is often called "natural convection".
Beneath the Earth's crust lies the mantle which is heated by the radioactive decay of heavy elements. The mantle is not quite solid and consists of magma which is in a state of semi-perpetual convection. This convection process causes the lithospheric plates to move, albeit slowly. The resulting process is known as plate tectonics.