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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 ...
The convection can simply peel away the lower crust or, in a different scenario, a Rayleigh–Taylor instability is created. Due to the instability in a local area, the base of the lithosphere breaks up into descending blobs fed by an enlarging region of thinning lithosphere.
Donald Lawson Turcotte (April 22, 1932 – February 4, 2025) was an American geophysicist most noted for his work on the boundary layer theory of mantle convection as part of the theory of plate tectonics. [3] He worked at Cornell University then the University of California, Davis.
[1]: 1 The realm of geochemistry extends beyond the Earth, encompassing the entire Solar System, [2] and has made important contributions to the understanding of a number of processes including mantle convection, the formation of planets and the origins of granite and basalt. [1]: 1 It is an integrated field of chemistry and geology.
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 ...
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 ...
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.