AP Env Sci (APES) Unit 4

Freshwater

Water that contains less than 1 percent salts.

Saltwater

Water in the oceans with high salinity.

Salinity

The concentration of dissolved salts in water.

Watershed / Drainage Basin

An area of land defined by elevated topography (called a divide), in which water from precipitation gathers and flows into a body of water such as a lake, river, or ocean.

Runoff

The water from rainfall that flows in a sheet over the surface of the land.

Percolation

The process by which water flows through spaces in soil and rock.

Water Table

The boundary between the zone of aeration and the zone of saturation, where groundwater saturates the spaces in soil and between rocks.

Aquifer

An underground supply of water that is contained in a layer of permeable rock.

Recharge

The water from precipitation that flows into a body of groundwater.

Upwelling

The process by which deep, cold water rises toward the surface to replace water pushed away by winds blowing at the ocean's surface.

Epipelagic Zone

The top zone of the open ocean; also known as the sunlit or euphotic zone.

Mesopelagic Zone

The middle zone of the open ocean; also known as the twilight zone because of the amount of light it receives.

Bathypelagic Zone

The deep zone of the open ocean; also known as the midnight zone because there is no light.

Abyssopelagic Zone

The bottom zone of the open ocean that extends to the seafloor.

Hadal Zone / Hadalpelagic Zone

This zone is found in deep-sea trenches and canyons even deeper and more forbidding than the ocean floor.

Gyre

A circular current in one of the world's major oceans.

Thermohaline Circulation

The circulation of deep ocean currents caused by differences in ocean-water temperature and salinity.

Tide

The regular rise and fall of the level of ocean water in an area that is caused by the gravity of the sun and moon and Earth's rotation.

Continental Shelf

The shallow, gently sloping part of the ocean floor near continents.

Mid-Ocean Ridge

A ridge of mountains beneath the ocean, formed by volcanic activity along a divergent plate boundary.

Young River

The part of a river near its headwaters, characterized by a steep stream gradient and no tributaries.

Mature River

The part of a river that has a moderate stream gradient, flows slowly in a wider, curving, U-shaped channel, and has many tributaries.

Old River

The part of a river that has a very low stream gradient, flows very slowly through a wide, U-shaped channel with many meanders, and has few tributaries.

Meander

A curve in the channel of a river.

Tributary

A smaller stream of freshwater that flows into a larger stream.

Floodplain

The flat area on either side of a mature river or old river that is covered by water when the river flows out of its banks.

Troposphere

The layer of the atmosphere closest to Earth, where all the weather occurs.

Stratosphere

The second layer of the atmosphere which blocks most of the harmful radiation of the sun.

Mesosphere

The third layer of the atmosphere, and the coldest of the layers.

Thermosphere

The fourth layer of the atmosphere.

Exosphere

The outermost layer of Earth's atmosphere.

Greenhouse Gases

An atmospheric gas such as methane, nitrous oxide, carbon dioxide, ozone, or water vapor that traps energy from the sun.

Climate

The average temperature and precipitation for a particular region.

Weather

The state of the atmosphere at a given time and place.

Jet Stream

A river of fast-moving air high above Earth's surface.

Convection

A zone of air in which warmer air moves upward in the center and cooler air moves downward at the edge.

Coriolis Effect

A change in the path of an air or water current due to Earth's rotation.

El Niño

A shift in the wind-driven movement of warm water in the Pacific Ocean that causes extreme disruptions to weather systems all over Earth.

La Niña

A lowering of the sea surface temperature by 3 degrees Celsius to 5 degrees Celsius across the equatorial Pacific Ocean that has extensive effects on the weather in North America.

Weathering

The breaking down of rock into smaller particles.

Mechanical Weathering

The breaking down of rock into smaller pieces by physical forces.

Chemical Weathering

The breaking down of rock into smaller pieces by chemical reactions.

Erosion

The movement of rock particles from one place to another.

Deposition

The settling of sediment.

Soil Horizons (O/A/B/C)

O horizon: The layer of undecomposed organic material lying on top of a soil. A horizon: The layer below the O horizon; it is well oxygenated and is high in organic matter and living organisms. B horizon: The layer below the A horizon; it is lower in organic matter but high in minerals that have been washed down from upper layers. C horizon: The layer below the B horizon; it consists of pieces of the parent material.

Humus

The mixture of organic molecules that result from decomposition but are largely resistant to further breakdown by organisms.

Porosity

The percentage of space not occupied by solid matter in a soil.

Permeability

The ability to transmit water or another fluid.

Loam

Ideal soil mix of sand, silt and clay; often described as good for plant growth.

Crust

The outermost layer of the geosphere, which can be between 5 and 70 kilometers thick.

Mantle

The thick layer of Earth below the crust composed of hot rock.

Core

The center of the planet, composed of solid iron and nickel (inner core) and the liquid layer of inner Earth that surrounds the inner core (outer core).

Lithosphere

The hard, rigid outer portion of the geosphere, including Earth's rocky crust and upper mantle.

Tectonic Plate

A large, moving piece of Earth's crust.

Convergent Boundary

A plate tectonic boundary at which the plates are moving toward each other.

Divergent Boundary

A plate tectonic boundary at which the plates are moving away from each other and new crust is being formed by volcanic activity.

Transform Boundary

A plate tectonic boundary at which two plates move past each other along the boundary.

Subduction

The movement of one plate, usually an oceanic plate, underneath another plate, usually a continental plate.

Epicenter

The point on Earth's surface directly above the focus of an earthquake.

Magma / Lava

Magma: Molten or partially molten rock that lies below Earth's surface. Lava: Magma that erupts onto Earth's surface.