AP Environmental Science Unit Four Vocab

Divergent Boundary

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

Convergent Boundary

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

Transform Boundary

An area where tectonic plates move sideways past each other.

Lithosphere

The outermost layer of Earth, including the solid upper mantle and crust. This is where the tectonic plates are located.

Hot spot

An area where magma from deep within the mantle melts through the crust above it

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.

Physical Weathering

The mechanical breakdown of rocks and minerals.

Chemical Weathering

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

Erosion

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

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.

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.

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.

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.

Hadley Cell

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

Coriolis effect

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

Upwelling

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

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 nino

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

La nina

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

Watershed

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