Ch. 10 The Oceans and Currents

waves

-Energy traveling along the interface between ocean and atmosphere -Derive energy and motion from wind

seawall

A barrier constructed to prevent waves from reaching the area behind the wall. Its purpose is to defend property from the force of breaking waves.

wave-cut platforms

A bench or shelf in the bedrock at sea level, cut by wave erosion.

emergent coasts

A coast where land that was formerly below sea level has been exposed either because of crustal uplift or a drop in sea level or both.

submergent coasts

A coast with a form that is largely a result of the partial drowning of a former land surface either because of a rise of sea level or subsidence of the crust or both.

estuaries

A funnel-shaped inlet of the sea that formed when a rise in sea level or subsidence of land caused the mouth of a river to be flooded

barrier islands

A low, elongated ridge of sand that parallels the coast.

longshore currents

A near-shore current that flows parallel to the shore.

deep-ocean circulation

A response to density differences

tombolo

A ridge of sand that connects an island to the mainland or to another island.

baymouth bar

A sandbar that completely crosses a bay, sealing it off from the open ocean.

wave-cut cliffs

A seawater-facing cliff along a steep shoreline formed by wave erosion at its base and mass wasting.

groin

A short wall built at a right angle to the shore to trap moving sand.

breakwater

A structure that protects a near-shore area from breaking waves.

marine terrace

A wave-cut platform that has been exposed above sea level.

sea arch

An arch formed by wave erosion when caves on opposite sides of a headland unite.

hard stabilization

An artificial structure built to protect a coast or to prevent the movement of sand along a beach. Examples include groins, jetties, breakwaters, and seawalls.

spit

An elongated ridge of sand that projects from the land into the mouth of an adjacent bay.

sea stack

An isolated mass of rock standing just offshore, produced by wave erosion of a headland.

circular orbital motion

As a wave passes, each bit of water moves in a near-circle and returns to where it started

gyres

Huge circular moving current systems dominate the surfaces of the oceans.

Why is deep-ocean circulation referred to as thermohaline circulation?

It is driven by ocean water density differences caused by temperature (thermo) and salinity (haline).

thermohaline circulation

Movements of ocean water caused by density differences brought about by variations in temperature and salinity.

List the world's 5 main gyres

North Pacific, South Pacific, North Atlantic, South Atlantic and the Indian Ocean Gyre

How do ocean currents influence climate?

Poleward-moving warm ocean currents moderate winter temperatures in the middle latitudes. Cold currents exert their greatest influence during summer in middle latitudes and year-round in the tropics. In addition to cooler temperatures, cold currents are associated with greater fog frequency and drought

What are the two factors that are most significant in creating a dense mass of water?

Temperature (cold water is dense) and salinity (density increases with increasing salinity)

beach nourishment

The addition of large quantities of sand to a beach system to offset losses caused by wave erosion.

Coriolis effect

The deflective force of Earth's rotation on all free-moving objects, including the atmosphere and oceans. Deflection is to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

What is the primary driving force of surface-ocean currents?

The ocean's surface currents follow the general pattern of the world's major wind belts. The positions of the continents and the Coriolis effect also influence the movement of ocean water within gyres

coastal upwelling

The process by which deep, cold, nutrient-rich water is brought to the surface, usually by coastal currents that move surface water away from the coast.

beach drift

The transport of sediment in a zigzag pattern along a beach caused by the uprush of water from obliquely breaking waves.

interface

a common boundary where different parts of a system interact

beach

an accumulation of sediment found along the landward margins of an ocean or lake

wave refraction

bending of waves

The tops of waves are called the ______ , which are separated by _______

crests, troughs

surface currents

develop from friction between the ocean and the wind that blows across the surface

shoreline features that form primarily due to erosion are called ________, whereas deposits of sediment produce __________

erosional features, depositional features

wavelength

horizontal distance between successive crests (or troughs)

Describe the motion of a floating object as a wave passes

it moves not only up and down but also slightly forward and backward with each successive wave

ocean currents

masses of water that flow from one place to another

Coastal winds combined with the Coriolis effect causes surface water to:

move away from the shore

circular orbital motion allows a wave form to:

move forward through the water, while the individual particles that transmit the wave move around in a circle

Halfway between the crests and troughs is the _______, which is the level that the water would occupy if there were no waves

still water level

How does the Coriolis effect influence ocean currents?

subtropical gyres move clockwise in the Northern Hemisphere and counterclockwise in the Souther Hemisphere

fetch

the distance that wind has traveled across open water

Interactions among different processes and relative important of each process of shoreline features depend on what factors:

the proximity of a coast to sediment-laden rivers, the degree of tectonic activity, the topography and composition of the land, prevailing winds and weather patterns, and the configuration of the coastline and near-shore areas

abrasion

the sawing and grinding action of the water armed with rock fragments

Why is the shoreline considered an interface?

the shore is the dynamic interface among air, land, and sea because these different parts interact at the shoreline

How does a wave's speed, length, and height change as it moves into shallow water and breaks?

the speed and length of a wave diminishes and the wave steadily grows higher until it's too steep to support itself and it collapses

wave period

the time it takes one full wave (one wavelength) to pass a fixed position

surf

the turbulent water created by breaking waves

wave height

vertical distance between crest and trough

The height, length, and period of a wave depend upon on 3 factors:

wind speed, length of the time the wind has blown and fetch

Coastal upwelling occurs in these areas when:

winds blow toward the equator and parallel to the coast