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A transport equation, usually of heat (sometimes of light element concentration): = + where T is temperature, = / is the thermal diffusivity with k thermal conductivity, heat capacity, and density, and is an optional heat source. Often the pressure is the dynamic pressure, with the hydrostatic pressure and centripetal potential removed.
Changes in Earth's magnetic field on a time scale of a year or more are referred to as secular variation. Over hundreds of years, magnetic declination is observed to vary over tens of degrees. [13] The animation shows how global declinations have changed over the last few centuries. [34] The direction and intensity of the dipole change over time.
Fluid motions occur in the magnetosphere, atmosphere, ocean, mantle and core. Even the mantle, though it has an enormous viscosity, flows like a fluid over long time intervals. This flow is reflected in phenomena such as isostasy, post-glacial rebound and mantle plumes. The mantle flow drives plate tectonics and the flow in the Earth's core ...
Earth cutaway from core to exosphere Geothermal drill machine in Wisconsin, USA. Temperature within Earth increases with depth. Highly viscous or partially molten rock at temperatures between 650 and 1,200 °C (1,200 and 2,200 °F) are found at the margins of tectonic plates, increasing the geothermal gradient in the vicinity, but only the outer core is postulated to exist in a molten or fluid ...
Shorter time scales mostly arise from currents in the ionosphere and magnetosphere, and some changes can be traced to geomagnetic storms or daily variations in currents. Changes over time scales of a year or more mostly reflect changes in the Earth's interior, particularly the iron-rich core. These changes are referred to as secular variation. [1]
Generated by the churning molten metals in Earth’s core, the magnetosphere shields the planet from harmful solar ... “It could change (its) rate, or even speed up again,” Brown said ...
fulfills that condition. Here = is the separatrix [13] separating the low latitude magnetosphere with closed geomagnetic field lines at θ ≥ θ m from the polar magnetosphere with open magnetic fieldlines (having only one footpoint on Earth), and τ the local time. θ m ~ 20° is the polar border of the auroral zone. q, Φ co, and τ co are empirical parameters, to be determined from the ...
During that time, researchers drilled a deep ice core that unearthed links between climate and atmospheric greenhouse gases over the past 800,000 years. The core collected during the latest ...