Notes Complete
Tide
periodic short-term change in the height of the ocean surface at a particular place, generated by long-wavelength progressive waves that are caused by the interaction of gravitational force and inertia; movement of Earth beneath tide crests results in the rhythmic rising and falling of sea level
½
Tides have wavelengths _____ Earth’s circumference:
Pytheas
_____ was the first to connect tides to the moon
Newton
Understanding of tides was developed by _____ in Principia
Newton’s Law of Gravitation
F = G(M₁M₂/r²)
Tide Generating Force
T = G(M₁M₂/r³)
46
The Sun’s gravitational influence is _____ % of the moon’s influence
Equilibrium Theory of Tides
idealized model of tides that considers Earth to be covered by an ocean of great and uniform depth capable of instantaneous response to the gravitational and inertial forces of the sun and the moon
1650
The center of the Earth-Moon system lies _____ km inside the Earth:
Gravity ; Inertia
The tidal bulges formed by the moon result from _____ and ____ :
Equal and Opposite
Gravitational and inertial forces are _____ at CE:
Tractive Forces
the net force of gravity and inertia, responsible for the two tidal bulges
Inertia
_____ causes the bulge opposite the moon
High Tide
the high-water position corresponding to a tidal crest
Low Tide
the low water position corresponding to a tidal trough
Lunar Tide
tide caused by gravitational and inertial interae-tion of the moon and Earth
24 ; 50
A tidal day is _____ hours and _____ minutes:
28.5
Tidal bulges can offset anywhere from _____ ° N or S due to the moon’s orbit
Solar Tide
tide caused by the gravitational and inertial interaction of the sun and Earth
Spring Tide
Neap Tide
the time of smallest variation between high and low tides occurring when Earth, moon, and sun align at right angles; neap tides alternate with spring tides, occurring at two-week intervals
Perigee
the point in the orbit of a satellite where it is closest o the main body
Apogee
the point in the orbit of a satellite where it is farthest from the main body
Perihelion
the point in the orbit of a satellite where it is closest to the sun
Aphelion
the point in the orbit of a satellite where it is farthest from the sun
30,600
The difference in distance between the perigee and apogee is _____ km:
3.7 million
The difference in distance between the perihelion and aphelion _____ km:
Dynamic Theory of Tides
model of tides that takes into account the effects of finite ocean depth, basin resonances, and the interference of continents on tide waves
1,600 ; 22
An idealized earth-tide model would have tidal waves moving at about _____ km/hr, where the depth of the ocean would have to be _____ km:
Depth
Tidal wave velocity is determined by ocean _____ :
Semidiurnal Tide
a tidal cycle of two high tides and two low tides each lunar day, with the high tides of nearly equal height
Diurnal Tide
a tidal cycle of one high tide and one low tide per day
Mixed Tide
a complex tidal cycle, usually with tvo high tides a tvo low tides of unequal height per day
US Eastern Coast, all Western/Northern European Coasts, Russia Northern Coast, majority of Greenland, all of Africa (except Somalia), Southern Mediterranean + Italy, Brazilian, Peruvian, and Argentinian Coasts, Australia East Coast, and New Zealand
Semidiurnal Tide Locations:
Antarctic Peninsula, Gulf of Mexico, Kamchatka region, Southwest Australia, South China Sea, and the Java Sea
Diurnal Tide Locations:
US West coast, North Mediterranean, Northern Central America, Chilean and Uruguayan coasts, Arabian Sea, Aleutians, Hawaii, Japan, Indonesia, and theGulf of St. Lawrence
Mixed Tide Locations:
Amphidromic Point
a "no-tide" point in an ocean caused by basin resonances, friction, and other factors around which tide crests rotate; about a dozen amphidromic points exist in the world ocean; sometimes called a node
Counterclockwise ; Coriolis Effect
Amphidromic circulation is _____ in the northern hemisphere because the _____ deflects the crest right:
5
The Pacific contains _____ amphidromic points:
Tidal Datum
the reference level (0.0) from which tidal height is measured
Mean Sea Level
the height of the ocean surface averaged over a few years time
Tidal Range
the difference in height between consecutive high and low tides
Small areas
Tidal range is small in _____ like lakes
Large enclosed basins
Tidal range is moderate in _____ like the Baltic or Mediterranean:
Large ocean basin
Tidal range is large in _____ , especially on coasts that concentrate tidal energy because of their shape:
Wide ; Symmetrical
A _____ and _____ basin forms a mini amphidromic point:
Narrow ; Enclosed
A _____ and _____ basin cannot rotate on an amphidromic point:
12 ; 24
Extreme tides occur where arriving tide crests simulation natural oscillations of _____ or _____ hours:
Seiche
The most extreme tides form from a combination with _____ resonance:
Tidal Bore
a high, often breaking wave generated by a tide crest that advances rapidly up an estuary or river
Tidal Wave
the crest of the wave causing tides; another name for a tidal bore; not a tsunami or seisinic sea wave
Higher ; Spilling
A tide crest moving into a river mouth is confined to move at speeds _____ higher than shallow-water wave at that depth, breaking into a _____ wave:
Predictability
The potential danger of tidal bores is combated by their ______ :
Bay of Fundy, southwest China the Amazon river, Ganges delta, and Severn River
Tidal bores are common in:
Maximum velocity
Tidal currents reach _____ midway between high and low tide:
Slower
Tidal currents are _____ in open sea because they are not confined:
1/100s per century
Tidal friction slows the rotation of the Earth a few _____ :
Tidal friction
The moon is tidally locked to the Earth because of:
Tidal Current
mass flow of water induced by the raising or lowering of sea level owing to passage of tidal crests or troughs
Flood Current
water rushing into an enclosed harbor or bay because of the rise in sea level as a tide crest approaches
Ebb Current
water rushing out of an enclosed harbor or bay because of the fall in sea level as a tide trough approaches
Slack Water
a time of no tide-induced currents that occurs when the current changes direction
Historical trends
Tide prediction is based off of:
3
Tide prediction is accurate to about _____ cm:
Meteorological Tide
a tide influenced by the weather; arrival of a storm surge will alter the estimate of a tide’s height or arrival time, as well as a strong, steady onshore or offshore wind
3
Intertidal marine organisms sort themselves into _____ subzones dependent on their toleration of submergence and emergence
Hanztschia
diatoms migrate through the west sand to photosynthesize at low tide
Fiddler Crabs
(Uca) shelter at high tide and feed at low tide
Sand Crabs ; Bean Clams
(Emertia) and (Donax) migrate up and down the beach for shelter and food
Grunion
(Leuresthes) spawn, deposit, and fertilize their eggs at high spring tide, the eggs are protected at low tide, and hatch at the next high spring tide
Tidal power
_____ is the only successfully exploited marine energy at a large scale:
1966 in France
The first tide generator was built in _____ , where both the tides and estuary output for power:
Low operating costs, free power, clean power
Pros of tidal power:
storm damage, easily corroded, alters resonance modes of bays/estuaries, disrupts sensitive marine life, tiny decrease in the rate of Earth’s rotation
Cons of tidal power: