Unit 6.2

Ocean currents

Are masses of water that flow from one place to another

Surface currents

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

• Primarilly move horizontaly

Deep Currents

Driven by differences in density, cause by the differences in ocean temp and salinity

• Move in vertical and horizontal directions

Gyres

a large system of circular ocean currents formed by global wind patterns and forces created by Earth’s rotation

They are in

• North pacific

• South pacific

• north Atlantic

• south Atlantic

• Indian ocean

Pycnocline

layer of rapidly changing density

What do surface currents follow

Move slowed than corresponding winds and follow the earth wind belt pattern

Coriolis effect

The earth spinning causes gases and liquid to deflect by the rotation of it

aridity

dryness — specifically, it refers to a lack of moisture in a climate or region.

What are factors that impact density

• Temperature : the colder the water, the denser it is

• Salinity: Density increase with increasing salinity

Waves

Energy traveling along the interface between the ocean and the atmosphere. They derive their energy and motion from wind

crest

Highest point/peak of a wave

trough

lowest point/valley of a wave

Wavelength

distance between 2 consecutive crest or trough

wave height

difference between crest and trough

amplitude

difference between the crest and a still water line

Wave Period

The time interval for one full wave to pass a fixed position

Wave height, length, and period dpeend on?

Wind

How does a wave in deep water act when approaching shore

as it approaches, the water becomes shallower and influences wave behavior. The wave starts slowing down and wavelengths decrease but the wave height comes higher. When it reaches a critical point, wave becomes to steep to support itself and collapses

what is wave erosion caused by

wave impacts and pressure

how do waves arrive to the shore

they arrive pralel to shore

Wave refraction

Waves arrive to shore parallel to it, the bend as they approach the irregular-shaped coastline

headland

a high, rocky piece of land that juts out into the sea.

• wave energy is concentrated against the sides and ends of headland when impacting it

Beach drift

process of sediment moving in a zig-zag pattern along the beach face

longshore current

refers to a current in the surf zone. It flow parallel to the shore and moves substantially move sediment than simple beach drift

Spit

A ridge of sand extending from the land into the mouth of an adjacent bay with an end that often hooks landward

Baymouth Bar

a sand bar that completely crosses a bay

Tombolo

A ridge of sand that connects an island to the mainland

Barrier island

Mainly along the Atlantic and gulf coastal Plain

Parallel the coast

Originate in several ways

factors that cause beach erosion

proximity to sediment-laden rivers

• degree of tectonic activity

• topography

• composition of land

• prevailing wind

• weather patterns

• configuration of coastline

Hard stabilization

Building structures

• Although they are shown not to be effective

Groins

Barriers built at a right angle to the beach that are designed to trap sand

Breakwaters

Barriers built offshore and parallel to the coast to protect boats from breaking waves

Seawalls

Armors the coast against the force of breaking waves

what are 2 alternatives to hard stabilization

Beach nourishment and Relocating buildings way from beach

Beach nourishment

adding sand to the beach system

how are shorelines classified

based on coastal changes

submergent coast

land adjacent to the sea subsides or the sea level rises

• Type of coastline btw

• include highly irregular shorelines and estuaries

Emergent coast

Type of coastline where there is an uplift of land or a drop in sea level

Spring Tide

During new or full moon, gravitational forces add together to create high high tides and low low tides. Large daily tidal range

Neap Tide

Happens in first and third quarters of the moon, gravitational forces offset and tidal range is the least

Ocean Basin

is essentially the entire underwater area of the Earth's surface that lies below sea level. It includes a variety of marine landforms that make up its structure. These landforms are shaped by tectonic, volcanic, and sedimentary processes.

Diurnal tidal pattern

• A single high and low tide each tidal day

• Occurs along the northern slope of the gulf of mexico

Semidiurnal tidal pattern

• 2 high and 2 low tides each tidal day

• Little difference in the high and low water heights = Small tidal range

Mixed tidal pattern

2 high and 2 low waters each day

Large inequality in high water heights, low water heights, or both

Prevalent along the pacific coast of the United States

Tidal currents

Horizontal Flows that accompany the rise and fall of tides

Flood current

Type of tidal current

• Water advances into the coastal zone

ebb current

type of tidal current

• Water moves seaward