Test 4: Dynamic Earth

Difference between tide and eustatic sea level change

tides: daily changes in elevation of ocean surface

eustatic sea level change: global sea level changes in volume of water in the ocean

Factors causing astronomical tides

earth and sun (based on their relative movement) which makes those tides predictable

Movement of water in tidal currents

A horizontal movement of water often accompanies the rising and falling of the tide.

Causes of spring and neap tides and their relationship to the phases of the moon

spring: when there is the greatest difference between high and low water. (new or full moon)

neap tide: least difference between high and low water. (1st and 3rd quarter moon)

Parts of a tidal curve

Taking the appropriate published time and height of high water (or time of low water for a low water curve) and the height of low water you are able to fill in you curve for the day.

Different types of tidal curves and what produces different tidal curves

\-diurnal, semidiurnal, and mixed

\-produced through high and low tides and the position of the sun and moon

Causes for variation in tidal time, height and ranges

the shape of the shoreline, the alignment of the sun, moon, and earth

Operation of an oceanic amphidromic tide

Amphidromic points occur because interference within oceanic basins, seas and bays, combined with the Coriolis effect, creates a wave pattern — called an amphidromic system — which rotates around the amphidromic point.

Future and past tides

can find out a rough prediction always based on the predictability of the position of the sun, moon, and the earth

Difference between deep-water and shallow-water waves

deep water: depth of the water is greater than 1/2 the wavelength

shallow water: occurs at depth shallower than the wavelength divided by 20

Changes in wave as approaches shore and breaking

as waves approach shore they "touch bottom" when the depth equals half of the wavelength, and the wave begins to slow down. As is slows, the wavelength decreases and the wave height increases, until the wave breaks

Development of wind-formed waves

wind-driven waves, or surface waves, are created by the friction between wind and surface water. As wind blows across the surface of the ocean or a lake, the continual disturbance creates a wave crest

Water velocity in standing waves

A standing wave has no water velocity

Movement of water in a rotary seiche

strong winds and rapid changes in atmospheric pressure push water from one end of a body of water to the other. When the wind stops, the water rebounds to the other side of the enclosed area. The water then continues to oscillate back and forth for hours or even days.

Factors controlling the period of a seiche

dependent on the bathymetry of the lake basin and on the effects of gravity and Coriolis forces

Development of cliffed coast and features that develop

A cliffed coast is a section of coast that has been cliffed by marine erosion or drowning.

Small bays, narrow inlets, caves, arches, and stacks

Parts of a beach and how they form

berms: relatively flat platforms often composed of sand that are adjacent to coastal dunes or cliffs and marked by a change in slope at the seaward edge.

beach face: wet sloping surface that extends from the berm to the shoreline

foreshore and backshore: look at defintions

Development of fair-weather and foul-weather beaches

fall in pressure is an indicator of foul weather

Coastal features that can develop from beach migration

barrier islands from as well as a change in shoreline

Cliffed coastal features

Small bays, narrow inlets, caves, arches, and stacks are usually the result of erosion along structural weaknesses, particularly bedding, joint, and fault planes, and in the fractured and crushed rock produced by faulting.

Parts of a beach

shoreline, foreshore, nearshore, offshore, beach face, berm, notch, etc.

Beach migration features

As the sea level rises, the barrier beach migrates landward, rolling landward over itself. The initial beach migrates landward over its own marsh into its second position. (lagoon, shoreface, barrier island, elevation)

Tides

Daily changes in the elevation of the ocean surface, the easiest ocean movements to observe

Eustatic sea level change

global sea level change related to changes in the volume of water in the ocean

astronomical tides

tides caused by inertia and the gravitational force of the sun and moon, predictable

meterological tide

a tide influenced by the weather, atmospheric pressure and wind, only as predictable as the weather

mean sea level

average of the highest and lowest tide levels of the ocean measured over a period of time

gravity

one of the major forces that controls tides, moons gravity causes oceans to bulge on both sides closest to the moon

centrifugal effect

Outward "force" directed away from center of rotation

bary center

point inside the earth, where the earth and moon orbit around

high tide

when water advances to its furthest extent onto the shoreline

low tide

when water recedes to its furthest extent

tidal current

alternating horizontal movement of water associated with the rise and fall of the tide

ebb tide

tidal phase during which water level is falling

flood tide

the tidal phase which the tidal current is flowing inland

slack water

a time of no current, occurs at high and low tides when current change direction, separates ebb and flood tides

tidal range

The difference in levels of ocean water at high tide and low tide, depends on time and location

spring tide

a tide just after a new or full moon, when there is the greatest difference between high and low water.

neap tide

a tide just after the first or third quarters of the moon when there is the least difference between high and low water.

syzygy

lining up of the moon, sun, and the earth (this is when tides are the most exaggerated)

new moon

A moon that is completely dark because it's unlit side is facing Earth

Half Moon

the Moon with half of its disk illuminated

full moon

moon phase when the entire side facing Earth is illuminated.

1st quarter moon

half of the moon near the sun is illuminated. moon is pulling on earth's water at right angle

3rd quarter moon

halfway between a full moon and the next new moon

tidal curve

height of water/time; most tidal curves two high/low tides per tidal day (24 hr. 50 m)

semidiurnal curve

two high tides and two low tides each tidal day with 2 high and 2 low at about the same height

diurnal curve

one low and one high tide for a daily tide

mixed tide

The tidal pattern of two unequal high and low tides daily

solar day

Earth's rotation period as defined by the position of the Sun in the sky; the time between successive passages of the Sun through the meridian

lunar day

Time between two successive overhead moons

24 hours, 50 minutes

solar declination

The latitude of overhead Sun; the place where one would go to find the Sun directly overhead at noon.

lunar declination

\-The moon's angular distance north or south of the equator

\-Creates diurnal and semidiurnal tides

apogee

(away) centrifugal bulge and gravitational bulge is shorter

perigee

(around) earth is moving fastest in its orbit so centrifugal effect is greatest and tidal bulge is moving its fastest

corange circles

Lines in an amphidromic system connecting all points experiencing the same tidal range.

amphidromic point

A nodal or no-tide point in the ocean or sea around which the crest of the tide wave rotates during one tidal period.

amphidromic system

A depiction of the large-scale rotary motion of the tides in ocean basins and seas that results from the Coriolis deflection of the tides.

windset

Temporary change in sea level associated with the wind-generated build-up of water against the shore.

barometric tide

Term for temporary changes in sea level associated with changes in atmospheric pressure, not caused by wind. (meteorological tide)

Progressive wave tides

the tide wave moving across the sea surface like a shallow water wave, wind generated waves

standing wave tide

when 2 equal waves are going in opposite direction and there's up and down motion on the surface but waves don't progress

Crest

Highest point of a wave

Trough

Lowest point of a wave

wave front

distance measured parallel to crest or trough

wave height

vertical distance between crest and trough

wave period

the time interval between the passage of successive crests at a stationary point

wave length

the horizontal distance between adjacent crests or troughs

wave frequency

The number of waves that pass a fixed point in a given amount of time

wave speed

distance that a wave travels, wavelength and frequency

wave stability

(progressive) wave steepness

wave celerity

speed of the wave

deep water waves

waves moving through water deeper than half their wavelength

shallow water waves

are waves in water shallower than 1/20 their original wavelength.

wave base

The depth below the surface where the circular orbits become so small that movement is negligible. It is equal to one-half the wavelength

mass transport

slow, onshore movement of water

Orbits

circular current in water created by passing waves

wave energy

form of renewable energy that can be harnessed from the motion of the wave, 1/2 potential and 1/2 kinetic

old seas

term for all the waves passing through an area which are not related to the current wave-generating conditions

potential energy

stored energy, stored by the position of water above or below the mean level of the water surface if no wave existed

kinetic energy

energy of motion, moving water, has momentum

fetch

The area over which the wind blows, as fetch increase so does height of the wave

capillary waves

The slowest moving waves, when wind blows across still water, creates irregular surface for wind to transfer energy

chop

when wind speed is greater than celerity (V shaped crests and land troughs)

white cap

A white, foaming wave with a very steep crest that breaks in the open ocean before the wave gets close to the shore

fully developed sea

the maximum wave size possible for a wind of a specific strength, duration, and fetch

swell

long wave of water that moves continuously without breaking; very fast low crested wave

wave dispersion

The separation of waves as they leave the sea area by wave size. Larger waves travel faster than smaller waves and thus leave the sea area first, to be followed by progressively smaller waves

wave reflection

when a wave bounces off of a hard surface that changes the direction of the wave

wave refraction

Slowing and bending of progressive waves in shallow water, affects the shoreline

wave interference

the phenomenon that occurs when two waves meet and produce sea surface distortion and then continue with no alteration

seas

complex sea surface distortion produced by wave interference

headland

a narrow piece of land that projects from a coastline into the sea.

breaking wave

The result of waves dragging on the ocean bottom causing the water in the waves to fall forward as the waves bunch together, rise up, and break against the shore.

undertow

strong seaward bottom current returning the water of broken waves back out to sea

surf

turbulent water created by breaking waves

wave setup

increase in mean of water level above still water level

longshore current

a near-shore current that flows parallel to the shore

rip current

a relatively strong, narrow current flowing outward from the beach through the surf zone and presenting a hazard to swimmers. (swim parallel to get out of it)

tsunami

A giant progressive waves usually caused by an earthquake beneath the ocean floor, not formed by constructive interference, not a tidal wave, japanese for harbor wave