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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 ...
Controversy over the exact nature of mantle convection makes the linked evolution of Earth's heat budget and the dynamics and structure of the mantle difficult to unravel. [21] There is evidence that the processes of plate tectonics were not active in the Earth before 3.2 billion years ago, and that early Earth's internal heat loss could have ...
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 ...
Convection within Earth's mantle is the driving force for plate tectonics. Mantle convection is the result of a thermal gradient: the lower mantle is hotter than the upper mantle, and is therefore less dense. This sets up two primary types of instabilities.
In geodynamics, dynamic topography refers to topography generated by the motion of zones of differing degrees of buoyancy (convection) in Earth's mantle. [1] It is also seen as the residual topography obtained by removing the isostatic contribution from the observed topography (i.e., the topography that cannot be explained by an isostatic equilibrium of the crust or the lithosphere resting on ...
It is because of these forces, slab pull, ridge push, mantle convection, and slab suction that the Earth's crust is able to move and orient itself in various arrangements. This is how throughout the Earth's history there has been the ability to create super continents where all of the land mass has converged into one (for example, Pangaea).
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
Because of the perceived fixity of some volcanic sources relative to the plates, he proposed that this thermal boundary was deeper than the convecting upper mantle on which the plates ride and located it at the core-mantle boundary, 3,000 km beneath the surface. He suggested that narrow convection currents rise from fixed points at this thermal ...