test 2 fr Flashcards
wave
an undulation in the ocean surface that results from some disturbing force, typically wind, seismic force, or gravitational
wave crest
highest point
wave trough
lowest point
wave period (t)
time between fixed points on waves
wave height
distance from trough to crest (twice the amplitude)
wave length
distance between same parts of two successive waves
frequency
number of waves that passes a fixed point per second. inverse of period
relationship between period and frequency
frequency is inverse of period
what happens to movement of water particles at depth as a wave passes through
water particles move in circular orbits
wave base
depth in the water above which a passing wave disturbs the water. below it is undisturbed.
how is wave base determined
1/2 wavelength
five types of waves
capillary, wind waves, swells, tsunamis, tides,
capillary waves
light breezes
wind waves
consistent wind. most common type.
what are wind waves controlled by
wind velocity, wind duration, and fetch
fetch
distance over which the wind is consistently blowing
tsunamis
tectonic forces, landslides, meteors
tides
gravity, centrifugal force
shallow water waves
long waves that interact with the water even in very deep OR waves in shallow water which is reached by smaller waves formed offshore
deepwater waves
progress through the ocean and do not interact with ocean floor. smaller waves produced in deep water
deepwater wave can lose its energy?
no, doesn’t lose energy or speed
speed of deepwater wave
dividing wavelength by wave period. Wavelength divided by period
as a deepwater wave becomes a shallow water wave, the speed
decreases
what are wave orbitals
circular path that water particles follow as waves pass
wave orbitals
decrease in size the deeper it is
shallow water wave orbitals
more elliptical, they reach the ocean floor
deepwater wave speed
L / t (wavelength /period) m/s
shallow water waves
3.13sqrtD (depth)
tsunamis and tides are
shallow water waves because they are extremely long waves in deep water
wave refraction
wave in deeper water continues at max speed, shallower part slows, eventually entire wave evens out when approaching the shore line
waves break at what ratio
height to length is 1:7
three types of wave breakers
spilling, plunging, surging
spilling breakers
result from waves of low steepness over gentle slopes. depositional, east coast and gulf
plunging breakers
steeper waves over moderate slopes. energetic, tall, provide barrels or tubes (pacific coast)
surging breakers
where beach slope exceeds wave steepness. waves don’t curl, just runs against shore and produced foam. (erosional shores)
tides
periodic short term changes in oceans surface’s height.
what are tides caused by
gravitational force of moon and sun, and motion of earth
what type of waves are tides
shallow water
development of tides understanding
pytheas - wrote about connection of moon position and tides. Newton said its proportional to their size and inversely proportional to the square of the distance between them (equilibrium theory). laplace came up with dyanmic theory
dynamic theory acknowledges
land masses, shallow water waves, circiular movement of tides while equilibrium doesnt
spring tide
increased height of the tidal wave. higher highs and lowler lows that occur during full and new moon cycles
neap tide
decreased height of tidal wave. lower high and higher lows, occur during quarter moon cycles
semidurnal tide
along atlantic coast, high tide to low tide occurs twice a day.
semidiurnal mixed tides
two highs and two lows, but different heights. (pacific)
diurnal tide
one high tide and one low tide (gulf of mexico)
ebbing
current of outgoing tide.
flooding
incoming tide
slack tide
lack of water movement when at the crest and trough
tidal bore
part of tidal rise in a river which is so rapid that water advances as a wall, often several feet high
which region of the shore do waves break for the first time
nearshore
berm
dry, raised portion of the beach above mean high water elevation. (where you put your towel)
sand dune
accumulation of windblown sand on backshore.
longshore drift
movement of sand along a beach (surfzone nearshore)
barrier islands
east coasts, protects mainland
summer erosion
less erosion, calmer weather
winter
higher, more erosion, rough weather
rip tide
strong offshore current that is caused by tide pulling water through inlet. tidal water flows steadily out to sea during ebb tide
dissipative beaches
occur where there is a gentle shore gradient in subtidal and intertidal area. wave energy is gradually dissipated. (waves break hundreds of meters offshore)
reflective beaches
are steeper, wave energy is reflected back to open water. have narrow beach and swash zones. no bar or surf zone
spilling breakers
waves that break several hundred meters offshore (dissipative beaches)
man made structures made to protect
jetties, groins, seawalls, offshore breakwaters
seawalls
build to prevent erosion of upland area
breakwaters
reduces wave energy and association erosion at the shoreline
dredging
removes sediment from offshore and places it nearshore
primary coast
shaped by land based processes (tectonic activity, river deposition, land erosion)
secondary coast
marine processes like wave erosion, deposition
sediment
particulate (larger undissolvable) material that settles to the bottom of the
what produces sediment
erosion, dissolution and deposition
how does water affect dissolution and erosion
can either dissolve or suspend sediment.
what allows water to be a universal solvent
water is polar (charged)
particulate material
does not dissolve in water
suspension
lighter material that can be suspended and carried great distances
saltation
large particles fall, then is picked up and moved, than falls
traction
heavier sediment can be gently nudged along the bottom
bigger the particle
faster they settle
what can affect how sediments are transported
size, density relative to fluid density, fluid viscosity, shape, chemical composition and charge
order of sediment from backshore, foreshore, nearshore, offshore
sand, muddy sand, sandy mud, mud
density
if density exceeds fluid density, particle sinks
viscosity
resistance to flow by the fluid medium. higher viscosity, more resistance, reducing settling rate
sediment from small to large
clay, silt, sand, granule, pebble, cobble, boulder
