Coastal Hazards - Coastal Processes Flashcards
The periodic rise and fall of sea level is known as
ocean tides
ocean tides are caused by
spinning motion of the Earth, combined with the gravitational interaction between the Earth, Moon, and Sun
refers to the difference in sea level between high
and low tides.
Tidal range
occurs when the Moon and Sun periodically line
up such that their gravitational effects reinforce one another
Spring tide
occurs when the gravitational pull of the Moon and
Sun are at right angles which tend to cancel their tidal effects on one another.
Neap tide
t or f: Earth’s oceans bulge outward because of forces created by the planet’s spinning motion
and gravitational interaction with the Moon and Sun.
t
t or f: the Moon has a greater tidal influence than the sun
t
these form as the surface of the Earth rotates in and out of the bulges within the oceans
ocean tides
also called the maximum tides
spring tides
three main tidal patterns:
diurnal, semidiurnal, mixed tidal pattern
diurnal means
daily
Characterized by a single high tide and single low tide each tidal day
diurnal
exhibits single two high tides and two low tides each tidal day
semidiurnal
semidiurnal tidal pattern is common along __________
Atlantic Coast of the United States
Similar to semidiurnal pattern except that it is characterized by a large inequality in high water heights, low water heights, or both.
mixed tidal pattern
in this tidal pattern, there are usually two high and two low tides each day, with high tides of different heights and low tides of different heights
mixed tidal pattern
mixed tidal pattern is prevalent along
prevalent along the Pacific coast of the United States and in many other parts of the world
on what phases of the moon does spring tide occur?
full moon and new moon
on what phases of the moon does neap tide occur?
first quarter and third quarter
are strong localized currents during high tide formed
by the surface of the sea sloping towards the shore which generates mechanical energy that forces water to funnel up into inlets and river channels.
Tidal currents
tidal currents generate __________ that forces water to funnel up into ________ and ________
mechanical energy ; inlets and river channels
tidal currents are formed by the surface of the sea ____________ the shore
sloping towards
involve the physical movement of water molecules
from one location to another, are driven by various forms of energy
ocean currents
currents flow from an area of _________ to ________
high energy to lower energy
are large scale currents in the open water near the
surface of the sea which are driven mainly by winds blowing consistently in the same direction.
surface currents
surface currents are driven mainly by
winds blowing consistently in the same direction
are formed in response to differences in ocean
temperature and salinity
density currents
Cooler and more saline water is relatively
________ which causes it to ______ and _______ toward areas where water is _________.
dense ; sink and flow; less dense
t or f: cooler water is denser
T
t or f: saline water is less dense
F (denser)
the movement of water from one location to another
currents
transport energy through water such that water
molecules move or vibrate in a circular manner.
water waves
Water waves transport energy in a ________ manner, but the___________ of water molecules causes physical objects to move in a ______ manner.
horizontal manner ; circular motion ; vertical manner
t or f: water waves transport energy in a horizontal manner
t
is the depth where water molecules are no longer
affected by the passing wave
wave base
wave base is equal to
one half of the wave’s wavelength
distance between successive crests of a wave
wavelength
contact area between the wind and water
fetch
The energy of wind generated waves is also affected by
- fetch
- duration of the wind
factors that determine the size and energy of waves
wind energy, duration of wind, fetch
the faster the wind speed, the ________ the wave energy
greater
the longer the wind blows, the _________ the waves
larger
the greater the fetch, the ____________ the wave has
the more energy the wave has
the circular motion of water molecule in a wave gets progressively __________ with depth
smaller
the level at which all movement stops
wave base
t or f: wave base get deeper with increasing wave energy
t
water from a breaker washing
upon a beach at whatever angle the breaker
approached shore.
swash
swash water retreating back
under the influence of gravity
backswash
t or f: Backwash takes the shortest path, direct to
the sea, not an oblique angle as taken by
swash.
t
t or f: backswash takes a path with an oblique angle
F (swash)
what are the two types of waves
constructive and destructive waves
this type of wave has stronger swash and weaker backwash, occurs on gentle sloping coasts, and deposits materials on the beach more than it removes.
constructive waves
this type of wave has stronger backwash and weaker swash, occurs on steep sloping coasts, and removes (erodes) materials on the beach more than it
deposits.
destructive waves
destructive waves occurs on _______ slopes ; constructive waves occur on _________
steep ; gentle
low waves in proportion to length
constructive wave
high waves in proportion to length
destructive waves
As the wave continues toward shore, this causes a progressive _________ in velocity along the ______ of the wave, forcing it to bend in a process called ________
decrease ; length ; wave refraction
____________ is a wave whose amplitude reaches a _________ at which some process can suddenly start that causes large amounts of wave energy to be transformed into _______________
breaking wave ; critical level ; turbulent kinetic energy
refers to the area where the waves break
surf zone
is an ocean current that flows parallel to the shore
and is caused by large swells (series of waves) sweeping into the shoreline at an angle and pushing down the length of the beach in one direction.
longshore current
a series of mechanical waves that propagate along the interface between water and air under the predominating influence of gravity
swells
is the process of transporting material
along a coast by waves which approach at an angle to the shore but recede perpendicular from it.
longshore drift or beach drift
longshore drift approach ________ to the shore but recede ________ from it
at ang angle ; perpendicular
t or f: friction causes waves to slow down
t
less friction slows down waves, this in turn causes __________ to _______ as the waves grow in height and become ___________, eventually waves become so _____ they fall on themselves and form breaking waves
wavelength ; decrease ; less asymmetric ; asymmetric
wavelength ________ and wave height __________ as waves get closer to the shore
decreases ; increases
as a wave approaches the land, the end closest to the shore encounters the seafloor first, forcing it to slow down while the other end travels at its original speed. this velocity difference results in _________ or _________ toward the shore
wave bending or refracting
Breaking waves push water up the beach, creating a _______ path as the water flows back into the surf zone
zigzagging
longshore current moves both water and sediment ________ to shore
parallel
can travel farther inland than the normal waves, this is due to the increased local sea level during storm events.
storm surges
t or f: Storms have the effect of not only generating waves but also increasing the height of the localized sea level
t
Large waves caused by the sudden mid/under sea displace of a large volume of water
tsunamis
tsunamis are caused by:
coastal landslides
mid-sea volcanic eruptions
calving
meteorite impacts
the glaciological term for the mechanical loss (or simply, breaking off) of ice from a glacier margin
calving
