Chapter 16 - The Dynamic Ocean

Ocean current

A directional movement of ocean water; surface currents result from steady winds over the ocean surface; deep ocean currents result from density variations due to temperature and salinity differences.

Surface current

A horizontal movement of ocean water that is caused by wind and that occurs at or near the ocean's surface

Neap tide

A less than average tide occurring at the first and third quarters of the moon when the sun and moon partially offset the influence of the other

How does energy move through a wave?

Circular orbital motion allows energy to move forward trough the water while the individual water particles that transmit the wave move around in a circle

tide

Daily changes in the elevation of the ocean surface

Name the three main tidal patterns

Diurnal tides, semidiurnal tides, and mixed tides

Wavelength

Horizontal distance between the crests or between the troughs of two adjacent waves

Gyres

Huge circular-moving current systems dominate he surfaces of the oceans

Why is upwelling important?

It brings greater concentrations of dissolved nutrients, such as nitrates and phosphates, to the ocean surface

What causes tides?

It is caused by the attractive forces of the Moon and Sun's gravitational fields as well as the centrifugal force due to the Earth's spin.

High latitudes

Most water involved in deep-ocean density currents begins in high latitudes at the surface

Name the main ocean gyres:

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

Denser water

Sinks and slowly spreads out beneath the surface

Tidal range

The difference in levels of ocean water at high tide and low tide

fetch

The distance that the wind has traveled across open water

Upwelling

The rising of cold water from deeper layers to replace warmer surface water.

How do surface currents develop?

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

Density current

Vertical currents of ocean water that result from density differences among water masses

How are sediments along the shoreline moved?

Waves along the shoreline are constantly eroding, transporting, and depositing sediment

How do ocean currents affect climate?

When currents from low-latitude regions move into higher latitudes, they transfer heat from warmer to cooler areas on Earth. As cold water currents travel toward the equator, they help moderate the warm temperatures of adjacent land areas

Spring tide

When the tidal range is greatest. (full moon and new moon)

What three factors affect the characteristics of a wave?

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

Erosional features

are shoreline features that originate primarily from the work of erosion

An increase in seawater density can

be caused by a decrease in temperature or an increase in salinity

How are density currents formed?

by differences in water temp and salinity

Mixed tides

characterized by a large inequality in high water heights, low water heights, or both (two high and two low tides each day but of different heights)

Diurnal tides

characterized by a single high tide and a single low tide each day

Longshore current

currents that flow parallel to the shore and move large amounts of sediment along the shore

Processes that increase water salinity

evaporation and the formation of sea ice

Semidiurnal tides

exhibits two high tides and two low tides each tidal day

From where do ocean waves obtain their energy?

from storms far out at sea over distances of several thousand kilometers

Tombolo

is a ridge of sand that connects an island to the mainland or to another island

Spit

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

Wave refraction

is the bending of waves

Coriolis effect

is the deflection of currents away from their original course as a result of Earth's rotation

Abrasion

is the sawing and grinding action of rock fragments in the water

Why is wave refraction important

it affects the distribution of energy along the shore

Processes that decrease water salinity

precipitation, runoff from land, icebergs melting, and sea ice melting

Beach

the accumulation of sediment found along the shore of a lake or ocean

Wave period

the time between a passage of two wave crests at a fixed point

Wave height

the vertical distance from the crest of a wave to the trough