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The current mantle plume theory is that material and energy from Earth's interior are exchanged with the surface crust in two distinct and largely independent convective flows: as previously theorized and widely accepted, the predominant, steady state plate tectonic regime driven by upper mantle convection , mainly the sinking of cold plates of ...
In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field. The dynamo theory describes the process through which a rotating, convecting , and electrically conducting fluid can maintain a magnetic field over astronomical time scales.
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 ...
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 may also take place in soft solids or mixtures where particles can flow. Thermal image of a newly lit Ghillie kettle. The plume of hot air resulting from the convection current is visible. Convective flow may be transient (such as when a multiphase mixture of oil and water separates) or steady state (see convection cell).
However, scientific communication in the 1930s and 1940s was inhibited by World War II, and the theory still required work to avoid foundering on the orogeny and isostasy objections. Worse, the most viable forms of the theory predicted the existence of convection cell boundaries reaching deep into the Earth, that had yet to be observed.
theory. For example, David M. Cutler and colleagues (2003) investigate whether or not the increase in caloric intake over time could be seen as simply a rational response to the lowered prices of food, in particular packaged snack foods, which are tempting to consume because they are convenient and require little time to prepare.
Numerical models of mantle convection in which the viscosity is dependent both on temperature and strain rate reliably produce an oceanic asthenosphere, suggesting that strain-rate weakening is a significant contributing mechanism, [24] and explaining the particularly weak asthenosphere below the Pacific plate.