The Solid Earth comprises a planet's solid inner core, liquid outer core, viscously deforming mantle, and mechanically stronger crust and lithosphere.
Mantle convection is the slow buoyancy-driven motion of a rocky planetary mantle. On geological timescales the solid mantle behaves as a highly viscous Newtonian fluid to first approximation.
The Rayleigh number compares buoyancy driving with viscous and thermal diffusion. For a layer of thickness , temperature drop , density , thermal expansion coefficient , gravitational acceleration , thermal diffusivity , and dynamic viscosity ,Thermal convection begins when this exceeds a geometry-dependent critical value.
A planetary ice shell is a solid water-rich layer overlying an ocean or deeper planetary interior. Its thickness can be controlled by thermal conduction, basal heat flux, surface radiation, and solid-state mantle convection.
A planetary surface energy balance equates absorbed short-wave radiation and heat supplied from below with reflected short-wave radiation and emitted long-wave radiation. With incident flux , Bond albedo , conductive upward flux , and emissivity ,
A Stefan problem is a moving-boundary problem in which a phase boundary moves as latent heat is released or absorbed. Temperature satisfies a heat equation in each phase and the Stefan condition supplies the interfacial energy balance.
The Stefan condition equates latent heat generated by motion of a phase boundary to the jump in conductive heat flux across it. With interface speed and normal directed from solid to liquid, one common sign convention is
A phase boundary is an interface separating distinct phases of matter. Its temperature, velocity, and flux jumps are constrained by phase equilibrium and conservation laws.
The Neumann solution places a planar phase boundary at . Similarity reduction of the heat equation gives temperature profiles in terms of the error function, while the Stefan condition determines implicitly.
Constitutional supercooling occurs ahead of a solidification front when rejected solute raises the local liquidus above the actual liquid temperature. The planar front can then become morphologically unstable because a displaced piece of solid enters supercooled liquid.
Glaciology studies glaciers, ice sheets, snow, and their interaction with climate, oceans, and the solid Earth.
Ice sheet dynamics describes the gravity-driven deformation and basal motion of large terrestrial ice masses together with their mass balance.
An ice cap is a dome-shaped terrestrial ice mass that flows outward from one or more ice divides and is smaller than an ice sheet.
The shallow-ice approximation uses the small ratio of ice thickness to horizontal extent to make pressure hydrostatic and balance its horizontal gradient primarily by vertical shear stress.
An ice divide is a line or point of maximum ice-surface elevation from which ice flows in opposite directions. Symmetry gives zero horizontal ice flux at the divide.
The snowline separates a region of net annual snow accumulation from a region of net ablation. A height-based idealization places it where the ice surface has a prescribed elevation .
Basal sliding is motion of glacier ice relative to its bed. A sliding law relates the basal velocity to basal shear stress, effective pressure, roughness, or other bed properties.
Postglacial rebound is uplift following removal of an ice load. It reflects viscous flow in the mantle and elastic or viscoelastic deformation of the lithosphere.
Glacial isostatic adjustment is the broader solid-Earth and sea-level response to growth and retreat of ice sheets.
Flexural isostasy models the lithosphere as an elastic plate that bends over a buoyant substrate. For a sinusoidal deflection of wavenumber , bending contributes a restoring stress proportional to , where is the plate's bending stiffness.
The Laurentide Ice Sheet covered much of northern North America during the last glacial period and left a major postglacial-rebound signal after retreat.
The Fennoscandian Ice Sheet covered northern Europe during the last glacial period and produced ongoing uplift around the Baltic region after retreat.
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Geophysics is the study of the Earth's physical properties and processes using quantitative methods and principles of physics. It encompasses a wide range of topics and techniques to investigate the structure and dynamics of the Earth, including its interior, surface, and the atmosphere.