Convection - Key terms
ASTHENOSPHERE:
A region of extremely high pressure underlying the lithosphere, where rocks are deformed by enormous stresses. The asthenosphere liesat a depth of about 60-215 mi. (about100-350 km).
ATMOSPHERE:
In general, an atmosphere is a blanket of gases surrounding a planet. Unless otherwise identified, however, the term refers to the atmosphere of Earth, which consists of nitrogen (78%), oxygen (21%), argon (0.93%), and other substances that include water vapor, carbon dioxide, ozone, and noble gases such as neon, which together comprise 0.07%.
BIOSPHERE:
A combination of all living things on Earth—plants, animals, birds, marine life, insects, viruses, single-cell organisms, and so on—as well as all formerly living things that have not yet decomposed.
CONDUCTION:
The transfer of heat by successive molecular collisions. Conduction is the principal means of heat transfer in solids, particularly metals.
CONVECTION:
Vertical circulation that results from differences in density ultimately brought about by differences intemperature. Convection involves the transfer of heat through the motion of hot fluid from one place to another and is of two types, natural and forced. (See natural convection, forced convection. )
CONVECTION CURRENT:
The flow of material heated by means of convection.
CONVECTIVE CELL:
The circular pattern created by the rising of warmed fluid and the sinking of cooled fluid. This is sometimes called a convection cell.
CORE:
The center of Earth, an area constituting about 16% of the planet's volume and 32% of its mass. Made primarily of iron and another, lighter element (possibly sulfur), it is divided between a solid inner core with a radius of about 760 mi.(1,220 km) and a liquid outer core about1,750 mi. (2,820 km) thick.
CRUST:
The uppermost division of the solid earth, representing less than 1% of its volume and varying in depth from 3 to 37 mi. (5 to 60 km). Below the crust is the mantle.
FLUID:
In the physical sciences, the term fluid refers to any substance that flows and therefore has no definite shape. Fluids can be both liquids and gases. In the earth sciences, occasionally substances that appear to be solid (for example, ice in glaciers) are, in fact, flowing slowly.
FORCED CONVECTION:
Convection that results from the action of a pump or other mechanism (whether man-made or natural), directing heated fluid toward a particular destination.
GEOSPHERE:
The upper part of Earth's continental crust, or that portion of the solid earth on which human beings live and which provides them with most of their food and natural resources.
HEAT:
Internal thermal energy that flows from one body of matter to another.
HYDROSPHERE:
The entirety of Earth's water, excluding water vapor in the atmosphere but including all oceans, lakes, streams, groundwater, snow, and ice.
KINETIC ENERGY:
The energy that an object possesses by virtue of its motion.
LITHOSPHERE:
The upper layer of Earth's interior, including the crust and the brittle portion at the top of the mantle.
MANTLE:
The dense layer of rock, approximately 1,429 mi. (2,300 km) thick, between Earth's crust and its core.
NATURAL CONVECTION:
Convection that results from the buoyancy of heated fluid, which causes it to rise.
PLATE TECTONICS:
The name both of a theory and of a specialization of tectonics. As an area of study, plate tectonics deals with the large features of the litho-sphere and the forces that shape them. As atheory, it explains the processes that have shaped Earth in terms of plates and their movement.
PLATES:
Large, movable segments of the lithosphere.
RADIATION:
The transfer of energy by means of electromagnetic waves, which require no physical medium (for example, water or air) for the transfer. Earth receives the Sun's energy via the electromagnetic spectrum by means of radiation.
SUBSIDENCE:
A term that refers either to the process of subsiding, on the part of air or solid Earth, or, in the case of solid Earth, to the resulting formation. Subsidence thus is defined variously as the downward movement of air, the sinking of ground, or a depression in Earth's crust.
SYSTEM:
Any set of interactions that can be set apart mentally from the rest of the universe for the purposes of study, observation, and measurement.
TECTONICS:
The study of tectonism, including its causes and effects, most notably mountain building.
TECTONISM:
The deformation of the lithosphere.
TEMPERATURE:
The direction of internal energy flow between two systems when heat is being transferred. Temperature measures the average molecular kinetic energy in transit between those systems.
THERMAL ENERGY:
Heat energy, a form of kinetic energy produced by the motion of atomic or molecular particles in relation to one another. The greater the relative motion of these particles, the greater the thermal energy.