DOCSLIB.ORG

Tides Throughout the Day, the Level of the Sea Rises and Falls. This Rise And

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Tides Throughout the Day, the Level of the Sea Rises and Falls. This Rise And Tides bore forms. A tidal bore can have a breaking crest or it can be a smooth wave. Tidal bores usually are found in places with large Throughout the day, the level of the sea rises and falls. This rise tidal ranges. When a tidal bore enters a river, its force causes water and fall in sea level is called a tide. A tide is caused by a giant in the river to reverse its flow. Waves in a tidal bore might reach 5 m wave produced by the gravitational pull of the Sun and the Moon. in height and speeds of 65 km/h. Although this wave is only 1 m or 2 m high, its wavelength is thousands of kilometers long. As the crest of this wave How does the Moon affect tides? approaches the shore, sea level seems to rise. This rise in sea level is called high tide. When the trough of this huge wave nears The Moon and the Sun exert a gravitational pull on Earth. The Sun the shore, sea level appears to drop. This drop in sea level is is much bigger than Earth, but the Moon is much closer. The Moon referred to as low tide. has a stronger pull on Earth than the Sun. Earth and the water in Earth’s oceans respond to this pull. The water bulges outward as the What is the tidal range? Moon’s gravity pulls it. This results in a high tide. The process is shown in the figure below. As Earth rotates, Earth’s surface passes through the crests and troughs of this giant wave. Many coastal areas, such as the The Moon’s gravity pulls at Earth. This creates two bulges of Atlantic and Pacific coasts of the United States, have two high water. One bulge is on the side of Earth closest to the Moon. The tides and two low tides each day. But because ocean basins vary other bulge is on the opposite side. The high tide on the side of in size and shape, some coastal locations, such as many along the Earth near the Moon happens because the water is being pulled Gulf of Mexico, have only one high and one low tide each day. A away from Earth towards the Moon. The high tide on the side of tidal range is the difference between the level of the ocean at Earth opposite the Moon happens because the gravitational pull on high tide and the level of the ocean at low tide. that part of Earth is greater than the pull on the water on that side of Earth. The areas of Earth’s oceans that are not toward or away Why do tidal ranges vary in different locations? from the Moon are the low tides. As Earth rotates, the bulges follow the Moon. This results in high and low tides happening around the Most shorelines have tidal ranges between 1 m and 2 m. world at different times. However, tidal ranges can be as small as 30 cm or as large as 13.5 m. What effect does the Sun have on tides? The shape of the seacoast and the shape of the ocean floor The Sun’s pull can add to or subtract from the gravitational pull of both affect the ranges of tides. A wide seacoast allows water to the Moon. Occasionally during Earth’s revolution, Earth, the Sun, spread out farther. At high tide, the water level might only rise a and the Moon are lined up together. Then, the Moon and the Sun few centimeters. In a narrow gulf or bay, the water cannot spread both pull at Earth. The combined gravitational pull results in spring out. The water will rise many meters at high tide. A narrow gulf tides on Earth. During spring tides, high tides are higher and low or bay will have a greater tidal range than a smooth, wide area of tides are lower than usual. When the Sun, Earth, and the Moon shoreline. form a right angle, high tides on Earth are lower than usual. Low tides are higher than usual. These are called neap tides. What are tidal bores? Sometimes, a rising tide enters a river from the sea. If the river is narrow and shallow and the sea is wide, a wave called a tidal 23. Define all words in bold. 24. How many tides do we have each day? Where only has one high and one low tide each day? Why? 25. How do tides differ depending upon where you are? 26. How does the Moon affect tides? 27. How does the sun affect tides? 28. Draw a picture the shows the relationship between sun, moon, and earth and when neap tides and spring tides occur. What is the continental shelf? ocean floor changes. When plates separate, hot magma from inside Earth erupts through small cracks, forming new crust. This process Ocean basins are low areas of Earth that are filled with water. is called seafloor spreading. The hot lava is cooled by ocean water They have many different features. Beginning at the ocean and hardens to solid rock. shoreline is the continental shelf. The continental shelf is the gradually sloping end of a continent that extends under the What are subduction zones? ocean. While seafloor is being formed along mid-ocean ridges, it is being On some coasts, the continental shelf extends a long distance. destroyed in other parts of the ocean. Areas where old ocean floor This is true for North America’s Atlantic and Gulf coasts. The slides beneath another plate and moves into Earth’s mantle are continental shelves on these coasts stretch 100 km to 350 km called subduction zones. into the sea. On the ocean floor, subduction zones are found within deep On the Pacific Coast, the coastal range mountains are close to ocean trenches, as shown in the figure on the previous page. A the shore. The shelf there is only 10 km to 30 km wide. The ocean trench is a long, narrow, steep-sided depression where one plate covering the continental shelf can be as deep as 350 m. sinks beneath another. Most trenches are found in the Pacific Basin. Ocean trenches are usually longer and deeper than any valley on What other features are found in the ocean? land. The Mariana Trench reaches about 11 km below the ocean The continental slope extends from the outer edge of the surface and is the deepest place in the Pacific Ocean. The Mariana continental shelf down to the ocean floor. Beyond the Trench is so deep that Mount Everest, the tallest mountain on Earth, continental slope lie the trenches, valleys, plains, mountains, and could easily fit into it. The figure below shows what it would look ridges of the ocean basin. like if Mt. Everest were placed in the Mariana Trench. How do abyssal plains form? In the deep ocean, sediment that comes mostly from land, settles constantly on the ocean floor. This sediment fills in valleys in the ocean floor and creates flat seafloor areas called abyssal (uh BIH sul) plains. Abyssal plains are from 4,000 m to 6,000 m below the surface of the ocean. In the Atlantic Ocean, some abyssal plains are large and extremely flat. The Canary Abyssal Plain has an area of approximately 900,000 km2. Sometimes abyssal plains have small hills and seamounts. Seamounts are underwater, inactive volcano peaks. Seamounts are most commonly found in the 29. Define all words in bold (7 in total). Pacific Ocean. 30. Draw the figure above and label it correctly. Ridges and Trenches 31. How deep is the Mariana Trench and what could fit in it? A mid-ocean ridge is a part of an ocean basin area where new ocean floor is formed. Mid-ocean ridges are found at the bottom of all oceans and form a continuous underwater ridge about 70,000 km long. Crustal plates, large section of Earth’s crust and upper mantle, are constantly moving. As these plates move, the .
Load more

Recommended publications
  • Time and Tides in the Gulf of Maine a Dockside Dialogue Between Two Old Friends
    1 Time and Tides in the Gulf of Maine A dockside dialogue between two old friends by David A. Brooks It's impossible to visit Maine's coast and not notice the tides. The twice-daily rise and fall of sea level never fails to impress, especially downeast, toward the Canadian border, where the tidal range can exceed twenty feet. Proceeding northeastward into the Bay of Fundy, the range grows steadily larger, until at the head of the bay, "moon" tides of greater than fifty feet can leave ships wallowing in the mud, awaiting the water's return. My dockside companion, nodding impatiently, interrupts: Yes, yes, but why is this so? Why are the tides so large along the Maine coast, and why does the tidal range increase so dramatically northeastward? Well, my friend, before we address these important questions, we should review some basic facts about the tides. Here, let me sketch a few things that will remind you about our place in the sky. A quiet rumble, as if a dark cloud had suddenly passed overhead. Didn’t expect a physics lesson on this beautiful day. 2 The only physics needed, my friend, you learned as a child, so not to worry. The sketch is a top view, looking down on the earth’s north pole. You see the moon in its monthly orbit, moving in the same direction as the earth’s rotation. And while this is going on, the earth and moon together orbit the distant sun once a year, in about twelve months, right? Got it skippah.
    [Show full text]
  • Moons Phases and Tides
    Moon’s Phases and Tides Moon Phases Half of the Moon is always lit up by the sun. As the Moon orbits the Earth, we see different parts of the lighted area. From Earth, the lit portion we see of the moon waxes (grows) and wanes (shrinks). The revolution of the Moon around the Earth makes the Moon look as if it is changing shape in the sky The Moon passes through four major shapes during a cycle that repeats itself every 29.5 days. The phases always follow one another in the same order: New moon Waxing Crescent First quarter Waxing Gibbous Full moon Waning Gibbous Third (last) Quarter Waning Crescent • IF LIT FROM THE RIGHT, IT IS WAXING OR GROWING • IF DARKENING FROM THE RIGHT, IT IS WANING (SHRINKING) Tides • The Moon's gravitational pull on the Earth cause the seas and oceans to rise and fall in an endless cycle of low and high tides. • Much of the Earth's shoreline life depends on the tides. – Crabs, starfish, mussels, barnacles, etc. – Tides caused by the Moon • The Earth's tides are caused by the gravitational pull of the Moon. • The Earth bulges slightly both toward and away from the Moon. -As the Earth rotates daily, the bulges move across the Earth. • The moon pulls strongly on the water on the side of Earth closest to the moon, causing the water to bulge. • It also pulls less strongly on Earth and on the water on the far side of Earth, which results in tides. What causes tides? • Tides are the rise and fall of ocean water.
    [Show full text]
  • Tsunami, Seiches, and Tides Key Ideas Seiches
    Tsunami, Seiches, And Tides Key Ideas l The wavelengths of tsunami, seiches and tides are so great that they always behave as shallow-water waves. l Because wave speed is proportional to wavelength, these waves move rapidly through the water. l A seiche is a pendulum-like rocking of water in a basin. l Tsunami are caused by displacement of water by forces that cause earthquakes, by landslides, by eruptions or by asteroid impacts. l Tides are caused by the gravitational attraction of the sun and the moon, by inertia, and by basin resonance. 1 Seiches What are the characteristics of a seiche? Water rocking back and forth at a specific resonant frequency in a confined area is a seiche. Seiches are also called standing waves. The node is the position in a standing wave where water moves sideways, but does not rise or fall. 2 1 Seiches A seiche in Lake Geneva. The blue line represents the hypothetical whole wave of which the seiche is a part. 3 Tsunami and Seismic Sea Waves Tsunami are long-wavelength, shallow-water, progressive waves caused by the rapid displacement of ocean water. Tsunami generated by the vertical movement of earth along faults are seismic sea waves. What else can generate tsunami? llandslides licebergs falling from glaciers lvolcanic eruptions lother direct displacements of the water surface 4 2 Tsunami and Seismic Sea Waves A tsunami, which occurred in 1946, was generated by a rupture along a submerged fault. The tsunami traveled at speeds of 212 meters per second. 5 Tsunami Speed How can the speed of a tsunami be calculated? Remember, because tsunami have extremely long wavelengths, they always behave as shallow water waves.
    [Show full text]
  • Tidal Hydrodynamic Response to Sea Level Rise and Coastal Geomorphology in the Northern Gulf of Mexico
    University of Central Florida STARS Electronic Theses and Dissertations, 2004-2019 2015 Tidal hydrodynamic response to sea level rise and coastal geomorphology in the Northern Gulf of Mexico Davina Passeri University of Central Florida Part of the Civil Engineering Commons Find similar works at: https://stars.library.ucf.edu/etd University of Central Florida Libraries http://library.ucf.edu This Doctoral Dissertation (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Electronic Theses and Dissertations, 2004-2019 by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Passeri, Davina, "Tidal hydrodynamic response to sea level rise and coastal geomorphology in the Northern Gulf of Mexico" (2015). Electronic Theses and Dissertations, 2004-2019. 1429. https://stars.library.ucf.edu/etd/1429 TIDAL HYDRODYNAMIC RESPONSE TO SEA LEVEL RISE AND COASTAL GEOMORPHOLOGY IN THE NORTHERN GULF OF MEXICO by DAVINA LISA PASSERI B.S. University of Notre Dame, 2010 A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Civil, Environmental, and Construction Engineering in the College of Engineering and Computer Science at the University of Central Florida Orlando, Florida Spring Term 2015 Major Professor: Scott C. Hagen © 2015 Davina Lisa Passeri ii ABSTRACT Sea level rise (SLR) has the potential to affect coastal environments in a multitude of ways, including submergence, increased flooding, and increased shoreline erosion. Low-lying coastal environments such as the Northern Gulf of Mexico (NGOM) are particularly vulnerable to the effects of SLR, which may have serious consequences for coastal communities as well as ecologically and economically significant estuaries.
    [Show full text]
  • How a Tide Clock Works.Pub
    Conventional time clocks have a 12 hour cycle, with 1 hand for hours, another for minutes. Tide clocks have a single hand, and a cycle of 12 hours 25 minutes, coinciding to an average time of about 6 hours 12 minutes between high and low tides. High tide is indicated when the hand is at the ‘12 o’clock’ position, low tide is indicated with the hand at the ‘6 o’clock’ position. A tide clock is not indicating 6 or 12 o’clock of course. It is merely a convenient reference point on the dial, showing us when our local tide is high or low. 12 is marked as High, 6 is marked as Low. However, the hour markings on the dial between the High and Low tide points do show us the number of hours since the last high or low tide, and the hours before the next high or low tide. A tide clock which has been initially set correctly will continue to display tide predictions quite accurately, requiring resetting only at intervals of about 4 months, depending upon the location. A brief explanation of how the tidal cycle works The Moon is the major cause of the tides. The ‘lunar day’ (the time it takes for the Moon to re-appear at the same place in the sky) is 24 hours and 50 minutes. New Zealand, and many other places in the world, have 2 high tides and 2 low tides each day. These are called semi-diurnal tides. Some areas of the world (eg Freemantle in Australia), have only one tide cycle per day, known as diurnal tides.
    [Show full text]
  • II. Causes of Tides III. Tidal Variations IV. Lunar Day and Frequency of Tides V
    Tides I. What are Tides? II. Causes of Tides III. Tidal Variations IV. Lunar Day and Frequency of Tides V. Monitoring Tides Wikimedia FoxyOrange [CC BY-SA 3.0 Tides are not explicitly included in the NGSS PerFormance Expectations. From the NGSS Framework (M.S. Space Science): “There is a strong emphasis on a systems approach, using models oF the solar system to explain astronomical and other observations oF the cyclic patterns oF eclipses, tides, and seasons.” From the NGSS Crosscutting Concepts: Observed patterns in nature guide organization and classiFication and prompt questions about relationships and causes underlying them. For Elementary School: • Similarities and diFFerences in patterns can be used to sort, classiFy, communicate and analyze simple rates oF change For natural phenomena and designed products. • Patterns oF change can be used to make predictions • Patterns can be used as evidence to support an explanation. For Middle School: • Graphs, charts, and images can be used to identiFy patterns in data. • Patterns can be used to identiFy cause-and-eFFect relationships. The topic oF tides have an important connection to global change since spring tides and king tides are causing coastal Flooding as sea level has been rising. I. What are Tides? Tides are one oF the most reliable phenomena on Earth - they occur on a regular and predictable cycle. Along with death and taxes, tides are a certainty oF liFe. Tides are apparent changes in local sea level that are the result of long-period waves that move through the oceans. Photos oF low and high tide on the coast oF the Bay oF Fundy in Canada.
    [Show full text]
  • A1d Water Environment
    Offshore Energy SEA 3: Appendix 1 Environmental Baseline Appendix 1D: Water Environment A1d.1 Introduction A number of aspects of the water environment are reviewed below in a UK context, and for individual Regional Seas: • The major water masses and residual circulation patterns • Density stratification (influenced principally by temperature and salinity) and frontal zones between different water masses • Tidal flows • Tidal range • Overall patterns of temperature and salinity • Wave climate • Internal waves • Water Framework Directive ecological status of coastal and estuarine water bodies • Eutrophication • Ambient noise Recent assessments of changes in hydrographic conditions are summarised, based mainly on reports by Defra (2010a, b) and MCCIP (2013) but incorporating a range of other grey and peer reviewed literature sources. Overall, significant anomalies and changes have been noted in sea surface temperature (SST), thermal stratification, circulation patterns, wave climate, pH and sea level – many appear to be correlated to atmospheric climate variability as described by the North Atlantic Oscillation (NAO). Larger-scale trends and process changes have also been noted in the North Atlantic (e.g. in the strength of the Gulf Stream and Atlantic Heat Conveyor (more properly characterised as the Meridional Overturning Circulation (MOC), or the Atlantic Thermohaline circulation (THC), northern hemisphere and globally. There are varying degrees of confidence in the interpretation of observed data and prediction of future trends. A1d.2 UK context There have been a number of information gathering and assessment initiatives which provide significant information on the current state of the UK and neighbouring seas, and the activities which affect them. These include both UK wide overview programmes and longer term specific monitoring and measuring studies.
    [Show full text]
  • Tide Clock Print Ver Instructions.Pub
    THANK YOU FOR PURCHASING THIS TIDE CLOCK An ‘AA’ size battery is required for operation. Insert into the holder on the rear of the movement A high quality battery will last longer and is also much less likely to leak corrosive fluid. Never leave a discharged battery in the clock. Properly cared for, this clock should provide years of service SETTING YOUR CLOCK Conventional time clocks have a 12 hour cycle. Tide clocks have a cycle of 12 hours 25 minutes. This coincides to an average time of about 6 hours 12 minutes between high and low tides. For the reasons outlined in more detail below, and to attain the best accuracy, it is recommended to first set the clock on a day when your local high tide coincides with a full Moon. Obtain a local tide table and calendar showing phases of the Moon from the links page of our website, www.cruisingelectronics.co.nz or your local newspaper, a Nautical Almanac or similar. On the day of a full Moon, use the small adjusting wheel on the rear of the clock movement to adjust the clock hand to the high tide position at your exact local time of high tide. Set in this way, the clock will exhibit a minimum error throughout the month, usually less than 30 minutes DO NOT adjust your tide clock for daylight saving time Please read below for a more detailed description of the tides and their influences. A brief explanation of how the Tidal cycle works The Moon is the major cause of the tides.
    [Show full text]
  • Physical and Dynamical Oceanography of Liverpool Bay
    Ocean Dynamics (2011) 61:1421–1439 DOI 10.1007/s10236-011-0431-6 Physical and dynamical oceanography of Liverpool Bay Jeffrey A. Polton · Matthew Robert Palmer · Michael John Howarth Received: 2 December 2010 / Accepted: 28 April 2011 / Published online: 31 May 2011 © Springer-Verlag 2011 Abstract The UK National Oceanography Centre has eastward erosion of the plume during spring tides is maintained an observatory in Liverpool Bay since identified as a potentially important freshwater mixing August 2002. Over 8 years of observational measure- mechanism. Novel climatological maps of temperature, ments are used in conjunction with regional ocean salinity and density from the CTD surveys are pre- modelling data to describe the physical and dynam- sented and used to validate numerical simulations. The ical oceanography of Liverpool Bay and to validate model is found to be sensitive to the freshwater forcing the regional model, POLCOMS. Tidal dynamics and rates, temperature and salinities. The existing CTD plume buoyancy govern the fate of the fresh water survey grid is shown to not extend sufficiently near the as it enters the sea, as well as the fate of its sedi- coast to capture the near coastal and vertically mixed ment, contaminants and nutrient loads. In this con- component the plume. Instead the survey grid captures text, an overview and summary of Liverpool Bay tidal the westward spreading, shallow and transient, portion dynamics are presented. Freshwater forcing statistics of the plume. This transient plume feature is shown in are presented showing that on average the bay re- both the long-term averaged model and observational ceives 233 m3 s−1.
    [Show full text]
  • MAR 110 LECTURE #22 Standing Waves and Tides
    27 October 2007 MAR110_Lec22_standing Waves_tides_27oct07.doc 1 MAR 110 LECTURE #22 Standing Waves and Tides Coastal Zone – Beach Profile Figure 22.1 Beach Profile Summer Onshore Sand Transport Breaking Swell Currents Erode Bar Sand…. & Build the Summer Berm Figure 22.2 Beach Evolution – Summer Onshore Transport 27 October 2007 MAR110_Lec22_standing Waves_tides_27oct07.doc 2 Winter Offshore Sand Transport Winter Storm Wave Currents Erode Beach Sand…. to form sandbars Figure 22.3 Beach Evolution – Winter Offshore Transport No Net Motion or Energy Propagation Figure 22.4 Wave Reflection and Standing Waves A standing wave does not travel or propagate but merely oscillates up and down with stationary nodes (with no vertical movement) and antinodes (with the maximum possible movement) that oscillates between the crest and the trough. A standing wave occurs when the wave hits a barrier such as a seawall exactly at either the wave’s crest or trough, causing the reflected wave to be a mirror image of the original. (??) 27 October 2007 MAR110_Lec22_standing Waves_tides_27oct07.doc 3 Standing Waves and a Bathtub Seiche Figure 22.5 Standing Waves Standing waves can also occur in an enclosed basin such as a bathtub. In such a case, at the center of the basin there is no vertical movement and the location of this node does not change while at either end is the maximum vertical oscillation of the water. This type of waves is also known as a seiche and occurs in harbors and in large enclosed bodies of water such as the Great Lakes. (??, ??) Standing Wave or Seiche Period l Figure 22.6 Seiche Period The wavelength of a standing wave is equal to twice the length of the basin it is in, which along with the depth (d) of the water within the basin, determines the period (T) of the wave.
    [Show full text]
  • Usually Undersea Earthquakes, Landslides, Meteor Strikes. Tsunami Are Not Like Wind Driven Waves, but Are Caused by a Change in the Basin in Which the Ocean Lies
    TSUNAMI Tsunami: These are caused by displacement – usually undersea earthquakes, landslides, meteor strikes. Tsunami are not like wind driven waves, but are caused by a change in the basin in which the ocean lies. Earthquakes are measured on the Richter Scale or the Mercalli Scale. The Richter Scale measures the amount of energy released whereas the Mercalli measures the amount of damage the earthquake is capable of. Here again scales are scientific artifacts produced with a specific goal in mind. Neither is right or wrong nor in conflict with the other. Tsunami do not look like breaking waves. Rather they look like an extremely high incoming tide. They appear as though someone has been adding more and more water to the ocean and the level keeps rising. Some serious Tsunamis: Santorini (Thera) An enormous volcanic eruption which produced a tsunami Somewhere around 1628 BCE Evidence from Greenland, California tree rings Climate affected – crop failure in Chine, part of Egypt impacted, (information appears on the stele of Ahmose). Some felt that this ended Minoan Civilization but archaeological evidence finds Minoan culture after the eruption. It is possible that the society was so damaged that it became perhaps too weak to defend against a very militant Mycene. There is some speculation that this eruption is the bases of Plato's Atlantis myth. Lisbon 1755 Nov, 1st at 9:40 am. (All Saints Day) Earthquake followed by a tsunami. People reported seeing the tide go out far enough to expose some ship wrecks. Churches where many had fled for protection were destroyed. Many candles which had been lit helped ignite fires all over.
    [Show full text]
  • Probable Late Messinian Tsunamiites Near Monte Dei Corvi, Italy, and the Nijar Basin, Spain: Expected Architecture of Offshore Tsunami Deposits
    Nat Hazards DOI 10.1007/s11069-011-9947-9 ORIGINAL PAPER Probable late Messinian tsunamiites near Monte Dei Corvi, Italy, and the Nijar Basin, Spain: expected architecture of offshore tsunami deposits Jan Smit • Cor Laffra • Karlien Meulenaars • Alessandro Montanari Received: 1 February 2010 / Accepted: 15 August 2011 Ó The Author(s) 2011. This article is published with open access at Springerlink.com Abstract Three distinct, 30- to 80-cm-thick, graded, multilayered, coarse-grained sandstone layers, intercalated in the late Messinian mudstones of the Colombacci forma- tion in Lago Mare facies of the Trave section are interpreted as tsunamiites (Ts1–Ts3). Each of these layers is sheet-like and could be followed along strike over several tens of meters. The lower two layers (Ts1–Ts2) occur in the lower part of the Colombacci for- mation and the third (Ts3) just below a conspicuous white ‘‘colombacci’’ limestone near the top of the formation. The three sandstone layers represent unique sedimentary events within the 120-m-thick San Donato-Colombacci mudstones, which contain many thin, fine- grained, possibly storm-related turbidites. Each of the three clastic layers is overall graded and strongly cross-bedded. A single layer consists of a stack of several graded sublayers that are eroded into the underlying mudstones and into each other. Absence of hummocky cross-stratification (HCS) indicates that the layers are not produced during a large, cata- strophic storm event. Current ripples such as dm-sized trough cross-beds suggest strong, prolonged, unidirectional currents, capable of carrying coarse conglomeratic sands. Climbing ripples in middle-fine sand units indicate a high suspension load settling under waning current strength.
    [Show full text]