APES Unit 4 Vocab

Core

Core

The innermost zone of Earth’s interior, composed mostly of iron and nickel. It includes a liquid outer layer and a solid inner layer.

Mantle

The layer of Earth above the core, containing magma, the asthenosphere, and the solid upper mantle.

Magma

Molten rock.

Asthenosphere

The layer of Earth located in the outer part of the mantle, composed of semi-molten rock.

Lithosphere

The outermost layer of Earth, including the solid upper mantle and crust.

Plate tectonics

The theory that the lithosphere of Earth is divided into plates, most of which are in constant motion.

Earthquake

A sudden movement of Earth’s crust caused by a release of potential energy from the movement of tectonic plates.

Hot spot

In geology, a place where molten material from Earth’s mantle reaches the lithosphere

Volcano

A vent in the surface of Earth that emits ash, gases, or molten lava.

Tsunami

A series of waves in the ocean caused by seismic activity or an undersea volcano that causes a massive displacement of water.

Divergent boundary

An area below the ocean where tectonic plates move away from each other.

Seafloor spreading

Caused by a divergent boundary, in which rising magma forms new oceanic crust on the seafloor at the boundaries between those plates.

Convergent boundary

An area where one plate moves toward another plate and collides.

Subduction

The process in which the edge of an oceanic plate moves downward beneath the continental plate and is pushed toward the center of Earth.

Island arc

A chain of islands formed by volcanoes as a result of two tectonic plates coming together and experiencing subduction.

Collision zone

An area where two continental plates are pushed together and the colliding forces push up the crust to form a mountain range.

Transform boundary

An area where tectonic plates move sideways past each other.

Fault

A fracture in rock caused by a movement of Earth’s crust.

Igneous rock

Rock formed directly from magma.

Sedimentary rock

Rock that forms when sediments such as muds, sands, or gravels are compressed by overlying sediments.

Metamorphic rock

Rock that forms when sedimentary rock, igneous rock, or other metamorphic rock is subjected to high temperature and pressure.

Rock cycle

The geologic cycle governing the constant formation, alteration, and destruction of rock material that results from tectonics, weathering, and erosion, among other processes.

Weathering

Weathering occurs when rock is exposed to air, water, certain chemical compounds, or biological agents such as plant roots, lichens, and burrowing animals. There are two major categories of weathering — physical and chemical — that work in combination to degrade rocks.

Chemical weathering

The breakdown of rocks and minerals by chemical reactions, the dissolving of chemical elements from rocks, or both these processes.

Acid precipitation

Precipitation high in sulfuric acid and nitric acid. Also known as Acid rain.

Erosion

The physical removal of rock fragments from a landscape or ecosystem.

Parent material

The underlying rock material from which the inorganic components of a soil are derived.

Horizon

A horizontal layer in a soil defined by distinctive physical features such as color and texture.

O horizon

The organic horizon at the surface of many soils, composed of organic detritus in various stages of decomposition.

Humus

The most fully decomposed organic matter in the lowest section of the O horizon.

A horizon

Frequently the top layer of soil, a zone of organic material and minerals that have been mixed together. Also known as Topsoil.

E horizon

A zone of leaching, or eluviation, found in some acidic soils under the O horizon or, less often, the A horizon.

B horizon

Commonly known as subsoil, a soil horizon is composed primarily of mineral material with very little organic matter.

C horizon

The least-weathered soil horizon, which always occurs beneath the B horizon and is similar to the parent material.

Porosity

The size of the air spaces between particles.

Water holding capacity

The amount of water a soil can hold against the draining force of gravity.

Permeability

The ability of water to move through the soil.

Cation exchange capacity (CEC)

The ability of a particular soil to adsorb and release cations.

Base saturation

The proportion of soil bases to soil acids, expressed as a percentage.

Watershed

All the land in an area that drains into a particular stream, river, lake, or wetland.

Insolation

Incoming solar radiation, which is the main source of energy on Earth.

Albedo

The percentage of incoming sunlight reflected from a surface.

Troposphere

A layer of the atmosphere closest to the surface of Earth, extending up to approximately 16 km (10 miles).

Stratosphere

The layer of the atmosphere above the troposphere, extending roughly 16 to 50 km (10–31 miles) above the surface of Earth.

Contains ozone

Ozone

A pale blue gas composed of molecules made up of three oxygen atoms

This ozone layer absorbs most of the Sun’s ultraviolet-B (UV-B) radiation and all of its ultraviolet-C (UV-C) radiation.

Mesosphere

The layer of the atmosphere above the stratosphere, extending roughly 50 to 85 km (31–53 miles) above the surface of Earth.

Thermosphere

The layer of the atmosphere above the mesosphere, extending 85 to 600 km (53–375 miles) above the surface of Earth.

Exosphere

The outermost layer of the atmosphere, which extends from 600 to 10,000 km (375– 6,200 miles) above the surface of Earth.

Saturation point

The maximum amount of water vapor in the air at a given temperature.

Adiabatic cooling

The cooling effect of reduced pressure on air as it rises higher in the atmosphere and expands.

Adiabatic heating

The heating effect of increased pressure on air as it sinks toward the surface of Earth and decreases in volume.

Latent heat release

The release of energy when water vapor in the atmosphere condenses into liquid water.

Atmospheric convection current

Global patterns of air movement that are initiated by the unequal heating of Earth.

Hadley cell

A convection current in the atmosphere that cycles between the equator and 30° N and 30° S.

Intertropical convergence zone (ITCZ)

The latitude that receives the most intense sunlight, which causes the ascending branches of the two Hadley cells to converge.

Polar cell

A convection current in the atmosphere, formed by air that rises at 60° N and 60° S and sinks at the poles, 90° N and 90° S.

Ferrell cell

A convection current in the atmosphere that lies between Hadley cells and polar cells.

Coriolis effect

The deflection of an object’s path due to the rotation of Earth.

Gyre

A large-scale pattern of water circulation that moves clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

Upwelling

The upward movement of ocean water toward the surface as a result of diverging currents.

Thermohaline circulation

An oceanic circulation pattern that drives the mixing of surface water and deep water.

Rain shadow

A region with dry conditions found on the leeward side of a mountain range as a result of humid winds from the ocean causing precipitation on the windward side.

El Niño–Southern Oscillation (ENSO)

A reversal of wind and water currents in the South Pacific.

La Niña

Following an El Niño event, trade winds in the South Pacific reverse strongly, causing regions that were hot and dry to become cooler and wetter.