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welcome back to an introduction to oceanography and chapter 10 essential of Oceanography that's the seventh edition by Tom Garrison and today we are talking about time and times are actually way they are forced to ways they are forced by gravity and inertia and they are the the waves on the planet they have the longest wavelength and they're essentially short-term changes ocean surface hi equilibrium theory applied explains tied by examining the balance
0:31
and that's forces though our plans day in orbit around the Sun when the moon to orbit the Earth because of the nearness to earth are gonna actually had a greater influence on our times than his son to the equilibrium theory basically looking the gravitational pull the Sun the Moon explained by the dynamic there he takes into account those but also see back on tour water viscosity and inertia together the equilibrium and dynamic carries a lot of time to be predicted an
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hour tomorrow actually your pants and one of the great things but I don't know what time will be good to know when the best herb is going to be you can also extract power from tidal flow right so kind of the longest of all ocean waves periodic short-term changes in the height of the ocean surface at a particular place caused by the gravitational force of the Moon and Sun and the motion of the earth the wavelength of tide can be half the
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circumference of the earth and are the longest I've always hide your considered forced way because they are never free from the forces that cause ever free from gravity the equilibrium theory of Todd's explains many characteristics of ocean the ocean surface is presumed always to be in equilibrium that and balance with the forces are acting upon it and dynamic theory of time to explain the characteristics based on the gravity of the Sun and the moon and the
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characteristics of fluid motion and also in the shape of ocean basins and the shape of the basis that times are acting it so the equilibrium theory again basically is looking at the gravitational forces playing to force the way theory thanks and all the other subtler aspects that dynamic duo remix hi calculations very complex things not a simple thing in a very complex formulas go into it once this phone call me essentially can know that i three years into the future
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gravity as we know holds bodies together a planet orbits the Sun in balance between gravity and inertia if the plan is not moving gravity will put into the Sun the planet is moving the inertia the plan will keep it moving in a straight line in a stable gravity and inertia or and balance and cause of Planet travel at a fixed at around the Sun so you have a non-moving planet being pulled toward the Sun and be the planet is moving in a direction in a straight line and of
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course number that binds to move in a straight line unless another forces celebration at upon them and so the gravity is that other force causing the motion of the planet be not necessarily more like it lives around the Sun so the pull of gravity between two bodies is proportional now this is what the force of gravity is full of gravity is proportional to the masses of the bodies at him wanted him to but it is inversely proportional to the square the distance between them by hand
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heavier objects generate more gravity and further the distance between two objects to less traveled to be heavy bodies are trying more strongly than bodies and bodies close together attracted so tired again our forests waves by gravity and and inertia had caused by the gravitational force the moon and the Sun and even though the size 27 million times as massive as the moon it's great distance from the earth means that its influence on art ideas about 46% of the
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mountains and that doesn't mean the moon exerts 54 percent and the power that exerted by the moon the Sun hits my forty-six percent of Newton's gravitational model to describe the urge tide is known as the equilibrium theory mainly considered the attractions of Earth Moon and Sun while giving some consideration to ocean depth or position no modification to the equilibrium is that dynamic theory which does take into account the wavelength of the wave water
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depth relationships to positions of the ocean basins the density of water seaboard biography or tree and lots of other race subtle change how times work in different places the movement of the Moon generate what's known as strong practice forces so in this example we see the distance between the Earth and the mass of the Earth 81 higher than that of the moon and what we know then is that the pivot point around which both the earth and the moon is this
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point just inside the earth's surface so the moon does not rotate around the center of the earth the earth and the moon together creating her own system and they rotate around a common share so the center is that better matches that point about a thousand miles beneath the earth's surface that's where that that lever is they're just not thousand miles nation outward force moving a straight line in the inward force of gravity are known as attractive forces so we can see
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that the average distance from the center of the center of the moon but because the artist so much more massive than the point at which the two were on each other's actually inside the earth's surface to the moon's gravity tracks the ocean thwarted the motion of the earth around the center of mass of the Earth system froze up a bold on the side of her opposite combination of the two banks create two voltages so in the first illustration you can see with it
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tractive force of the rabbit in the moon literally pulled the ocean's surface toward it and create a bulbs on that side of the earth the earth then around that math system then forces in opposing bulge on the opposite side of the motion around that moving around that center and that trades that opposite where that opposing bulge in the combination and he any given moment you have a bolt create about the gravity of the Moon pointing toward the opposite side you have a ball
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Genesee service this is this bold represent the sea service without the moment the sea surface be flat around with them as you see in the leftovers duration is stored in the motion of the earth and the earth-moon system is about away from the combined result is this bulge in the sea surface pointing toward an important later those at high tide as you know the Earth revolves on an axis it spends on taxes and spending on its axis that then Hodges and beach to go
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from high tide low tide so here's a very detailed explanation of this you should take a few moments maybe possibly oh and read some of the very specifics about this where you have different forces at different points on your forces created by inertia forces created by gravity tractor forces and then how they all sort of balance together in the end the two forces that movie ocean which is one of the nurses on the planet surface because our system and the gravitational
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attraction soon they are precisely equal in strength but their opposite direction so that ownership and the gravitational attraction to the moon is the same but just an opposite direction and so they balance balance at the center of the earth that's the center their CD point the action of gravity and inertia articles at five locations are shown here so we see it one two three four and then 15 appoint one or two the gravitational attraction the moon
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slightly exceeds the gravitational attraction them slightly CT how we're moving tendency of inertia the imbalance of forces causes water to move along the earth's surface converting a point toward the moon at three and four inertia exceed the gravitational force of water on the Earth's surface and converted a point opposite so it is that motion of the water along earlier service because on the side closest to the gravitational attraction exceeds a
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waiting hearse exceeds gravitational attraction that causes the water removal on the inner surface in the bulge up there right in the center so again you get a boat toward the opposite the courses result underneath that bulge and that is how it goes I kinda low tide generates those strong attractive forces the water bowls resulting from a nurse she is on the back side of the Europe gained a lot of voters Altinkum reputation is on the front side near
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there is not a point on the tractor forces are in equilibrium only dissenter service they're not so then extract divorces in the service cause the water to move for those involved one pointing toward in there and when 2008 beside the movement of the planet means at one point you can be under low tide and another point you're going to be under the ball use a long day the boat just a line the Earth Moon system doesn't change dramatically over the course of
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24 hours it does the moon takes 28 days to get around the moon along its path around but in a given 24 hour period it's it's it's and so that bulge essentially stage puts the ball just stays on line at the earth spend axis Earth's rotation beneath the terrible twos produces high tides and low tides and we can see if I look at this that the title side was about 24 hours 50 minutes long that because the moon is gonna come up about 15 minutes
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later each day because a bitch trip around the earth every month or so so it doesn't come up at the same time comes up a little bit later and because of the time change by anywhere between fifty and 42 maybe sixty minutes today and what space in Europe and again we're looking down on the earth turns these were last year underneath a title and at one point six turning them 6:30 in the morning high tide 12:26 yellow tie and that's as that tends to that I double
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bogey isn't moving the boat is fixed and that bulge of lunar day is the time that elapses between the time the moon highest in the sky and the next time is highest in the sky and a twenty-four hours solar day moves eastward by about 12.2 degrees so earth must rotate another 12.2 degrees for about 15 minutes to again place the moon at its highest position over a lunar day is 24 hours and 50 minutes long because it must earn an additional 15 minutes for
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the same title and we were tired usually arrive about 50 minutes later each day again the dynamic doing other factors involved change that not exactly but it did not have a minute later each day lunar tide Tide caused by the gravitational in their arsenal so there's another directly overhead star and then as you go around one soldier day the moon had moved 12.2 degrees and say you got you have to travel another 50 minutes to
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catch up to it and that's why the tide on exactly aligned every day that's why they're not fifteen minutes later each day so the title of Beaulieu will follow the room so that kind of bulbs will new again with the moon and why are tied to different everyday did not always they directly above the equator and tidal bulges followed him into not only is the moving ahead 12.2 degrees each day it's not always directly aligned with the equator because it's not always directly about
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the equator that bulges gonna follow the moon when the position his north of the Equator the gravitational pull toward men is also located and the opposite inertial bulge is below the equator so yeah just signed it also influence but I kinda hard 'cause gravitational force of the Moon and Sun and even though the Sun is 27 million hi it's great distance from the earth mean that influence high design about 46% forces developers and waited but in reality it's not just the
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one bulge of the moon is gonna be one large bowl gently decide the order because of Nerja but there's also going to be a smaller balls that is created by the Sun so the soundtrack of course is developing the same way as the moon but smaller boats falls under the game's over time courses of the Earth and Sun very much the same way as with the minute like the moon the Sun also positioned directly above the equator slowly to the position of the solar balls varies just the same way
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position available again we're talking about that north and south of the Equator the equinox or the beginning of fall of the inning as spring descended directly over the equator and that's what our goal should be but we go into the Northern Hemisphere winter and where tilted away from the Sun to go down you have the truck that's where those will be the same thing we're going to our cancer and that's what are in line with the earth in the solar and lunar tides
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attitude called springtime a right angle to this other types of dementia and other time to call need time so this is where records to the cells back online in the disorder called call springtime the solar time I don't need type so what this looks like so when you have again so here's the sun shining on the middle east side so what we see at night is dark here's the sun shining on the other than the full half of them going to be eliminated so that's going to be a full and so when you have
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a minute on the opposite side it could produce bolts further out in this weather out when the moon is that right ok then the motor boat is here and the villages here and solar boat is here and so you've lessen the time this situation here adding adding disorder or subtracting up so you know I time are going to be higher during the spring time the attitude and your low tide of any lower than hear your height I do not to be quite high
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but you're low tide is gonna be a little bit higher as well so bottom line is that the new one phone call in a minute I to reinforce each other making springtime at the first and third quarters the Sun and the right angle creating need tied the lowest and highest lows below highs and the highest close relative position of the Sun during spring in all the new full moon solar each other making the springtime the highest high and the lowest low to
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prison for writing me time the lowest high and the highest loti here you can see the title record for two CDs New York City and Port Adelaide Australia and the impact of the phases of the Moon remember the new design and Miller lineup that create the type you're going to be higher in the quarter you are going to have lower but your actual low tides will be higher ISO there's definite changes between this spring hide and the need tied and they all
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follow the phase of the moon and again the moon is not always an exact same position over the earth everyday changes by about 50 minutes so this all fluctuate I would be very hot today and then you know other factors that determine when high tides and low tides according to occur so it never all exactly the same one day to the next one month in extra one year test the dynamic area but I explain the difference between the predictions of
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the equilibrium theory and the observed kinds of the equilibrium theory would predict one thing the actual observed tied or something different and we use the dynamic theory to explain the difference it recognizes that water covers only three quarters the planet and is confined shallow seas ocean basins you also understand the shape of those bases may induce different types of movements including seizures water sloshing back and forth or circular it
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also takes into account this feed the long way to hide and relatively shallow waters tides are always shallow water way they always feel the bottom so we have different types of time three basic different types of tied to my girl diurnal next to the word dying on a daily you probably aren't they with the idea of something being nocturnal something that occurs at night cats are nocturnal animals they do most of activity at nighttime will die on me
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daily so that means twice today how today's twice a day diurnal means that once a day and there's a mixed I so Cindy diurnal tides occur twice a day then eluted a diagonal times what each day and then mixed times describing how was significantly different highs and lows through a cycle now within all basins there's an effort run a point or a drama point which are also known as the animatronic point are known as a No kind point where the water
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does not change at the center of ocean basins this is where the water level does not change so here is an illustration globally where you have mixed like Los Angeles we have some time high sometimes sometimes higher load Laredo this diagonal time meaning one high and 100 typically have in the Gulf basin because the water is back and forth and then we have a long the east coast when you see on the big chunk of the world's coastlines this
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site where you have one too high to low tide in any lunar day so he hampered roaming regulation tied way dressed in her as an ocean basin in the northern hemisphere that it was happening so what time wave moved into an ocean basin in the northern hemisphere to waive trends to the right because of Coriolis odd thing to hide time on the base in eastern shore unable to continue to the right because then get affected northward or to the north
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follows the shoreline that causes a high time on the basis of northern short next in the wait continues its progress around the base and counter clockwise rotation forming a high tide in the west and short third and then completing the circle the point at which the crest moved that point at which the grass and lose his temper drama point or the AP and that is a point where the water level doesn't change the tide rotates around that point and it may be
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counter-intuitive it rotates counterclockwise because being forced to the right clockwise here but it's not worse than a 90 degree angles where's the party by Wade hit the coast and angle and his deflected north and that's why I routes around the basin counterclockwise so these city and Pedroia points and all the world's oceans and you can see the North Atlantic has 11 sorted in the caribbean you have one down in the southern parts
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of the South Atlantic Pacific is a couple accident and the epidemic points are points which tides rotate around the bases so tidal ranges generate increasing with increasing distance from the AP so the further you get away from the drama coined the morning you're gonna have a range of ties the colors indicate were tied for most extreme the highest highs and lows lows of Blues being leased extreme and in the red being the most extreme we do have a very extreme
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high and low tides at great distances from the eighties white lines radiating from the AP indicating tidal waves moving around these points so there's almost a dozen places on the map with online converge to be here aP's notice how each of these places the surrounding caller the title horse never even blew dat this little or no guarantee that Emperor draw me know that point which there's no typing no tie point these areas are dropping points time waves
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move around these points clockwise in the northern hemisphere encounter in the northern hemisphere clockwise in the southern hemisphere as you point out this whole motion around these very specific point is why high just a different to me different parts of the world and these plans change over geologic time as our cotton it and ocean basins slowly change their shape either increasing or decreasing inside changing the shape in general these note I'd points will change as well just an
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extremely slow process so tidal patterns vary with ocean basin shape in time experience certainly allow the prediction of Thai heights to an accuracy of 210 for literally years into dance the tidal range is the height difference in height I loti now in some analysts or other enclosed the basin essentially you get a title phenomenon in which the leading edge of the incoming literally forms away so that I is moving against water coming in an inlet and so we're a tidal bore forms is where the
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leading edge of the incoming tide literally form waiving some cases multiple ways of water that travel up the river or narrow base in Italy travel against the direction of the river base current now we also need time her and bays and harbors you have the flooding current which is when the tide is is crafted yeah what's known as current which is when its lowest point in slack water is the time when there's no water moving in or out of the barrel the
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highest amount of water they are beautiful at her lowest amount you don't have to earn between calls flatwater so here's some interesting ocean basins and an interesting title 60 did you look at the open ocean in the left AP right in the rotation the water moves in the basement deflected to the right strikes the coastline on the east side and just travel around coastline paying $10 you have a similar situation occurs up in the Canadian Maritime Provinces
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but the islands and the shapes the coastline deflect and change those guys so it's not exactly a rehearing take into account the dynamic theory so this time arranged determined by the basic configuration so the imaginary AP system and abroad shalaby numbers indicate our position of the tigresses cycle progresses the AP system for the Gulf of st. Lawrence again which is a canadian maritimes between south eastern Canada the dashed line shows the time Heights
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High is passing so you get some pretty significant higher heights moving to this baby clothes different unusual and unique shapes and he look at the bottom left corner too bad but andy is a title they they had with the largest tidal ranges the world with his literally twenty or thirty curse so narrow base in like you see in that there's no eight pieces and there's really no 87 narrows is no space for rotation so we see like a band Fundy the water just come
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straight in and then go straight back out and create essentially seashore water and water rushes down 50 metre title reign the Bay of Fundy
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now we're going to talk about and how they affect marine organisms and within an intertidal zone with the kind who was low to high tide organisms are exposed to varying amounts of emergency and submergence under the water so the dramatic effect organisms that can live there is a small fish they time their reproductive behavior to precisely coincide with get up on shore I drink very very low tide and later a ride on shore and you ever heard the grunion run in california
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these pop up on shore right at the edge of the water and literally lay their eggs in the sand and then add the water rushes back up to the lowest I did this season the water comes back up a composition and water in the Navy beings baby fish underwater that's the grunion run and these grunion manheim they're laying their eggs precisely to the lowest low tide at the season and of course there are a lot of other creatures that you find what are known
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as tide pools pools of water they left behind it go up and down and always find a way to type full words into the crap different things seen me maybe even though she cucumbers a fine tidal pools so they also have talked a little bit about the power that can be extracted from title motion trap hichi water can be generated use electricity to the tide comes in so he goes up it's going up slow to push ups lo into the force of gravity is gonna
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pull it back down at the time goes too low and we can use it for sobriety and water to create electricity the first major title power station was opened in 1966 bosses Korea eventually they submerged turbines in open water to allow that tide pushing back and forth as it did to drive turbines
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didn't fight in a new source of energy is emerging the size of a submarine here at the dockside at least the Edinburgh last we power machine nearby mountains of code it was cold that fueled the industrial revolution could see power be next and this component is now being lowered into the sea operations will have to be repeated thousands of times the start of what being described as a new era harnessing the power of the sea and the Assembly Hall I was given the
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chance to see and sign down through the house like being inside a summary it's a strange new technology so far its cost some 40 million pounds out at sea will be no one in here to deal the rocking of the way and here at the end of this giant cylinder generating
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done everything away along this system does move huge hydraulic pumps like bicycle pumps and that the waves is channeled into a generated like this and end up producing electricity cables will bring the power there are no way but the contribution average with the year every major what we generated a megawatt didn't read my reviews this plan to harness the power of the sea is the largest of its kind in the world electricity than 750,000 homes could be produced it all the projects go ahead
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that's 1.2 gigawatts what a conventional power station generates a bold ambition from the official agency leasing out ten areas have seen as a very important day we've actually done is taken a very big step to making a new technology renewable energy technology wave and tidal commercially deployed address on a big scale the designs range from wave machines weighing in the swim two giant turbines spinning in the ties huge propellants harnessing the currents
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another component is unexpected costs or challenges it's still early days needed treatment BBC news so there are some very exciting possibilities with tidal power 200 low operating costs of course it's a free power source the low operating costs is to operate machinery to build it put in place that can be expensive the biggest disadvantage kind of power is that even if you built stations in every place in the world where you can use them you probably
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would only generate about one percent of the current world need not necessarily worldwide solution to power generation although it may be one solution so just to summarize chapter 10 times are the longest of the oceans waves they are forced waves forced by a combination of gravity can be heard in China and it affected by the motion of the earth contours and shape the ocean basins and a couple of other factors and how water tends to move within ocean basins and rocket specific frequency all those
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things are part of the dynamic period unlike other way these massive shallow water long wavelength wave are never free of the forces that cause them to be a Canon usual but generally predictable ways and again that dynamic theory of wave tradition and basins as we learn I can resonate basin residences and other factors combined to cut different title patterns and different coastline remember you have diagonal title like an in-close basin up down one time I went I
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love each day how their coastline more open coastlines have had mixed type so different basin different types of time and the rise and fall of the tide can be used to generate electrical power dream for many physical and biological coastal processes my dad is gonna wrap up chapter 10 we will see you these will be together again for chapter 11
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