Tidal Analysis and Predictions
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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. -
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. -
The Double Tidal Bulge
The Double Tidal Bulge If you look at any explanation of tides the force is indeed real. Try driving same for all points on the Earth. Try you will see a diagram that looks fast around a tight bend and tell me this analogy: take something round something like fig.1 which shows the you can’t feel a force pushing you to like a roll of sticky tape, put it on the tides represented as two bulges of the side. You are in the rotating desk and move it in small circles (not water – one directly under the Moon frame of reference hence the force rotating it, just moving the whole and another on the opposite side of can be felt. thing it in a circular manner). You will the Earth. Most people appreciate see that every point on the object that tides are caused by gravitational 3. In the discussion about what moves in a circle of equal radius and forces and so can understand the causes the two bulges of water you the same speed. moon-side bulge; however the must completely ignore the rotation second bulge is often a cause of of the Earth on its axis (the 24 hr Now let’s look at the gravitation pull confusion. This article attempts to daily rotation). Any talk of rotation experienced by objects on the Earth explain why there are two bulges. refers to the 27.3 day rotation of the due to the Moon. The magnitude and Earth and Moon about their common direction of this force will be different centre of mass. -
Lecture Notes in Physical Oceanography
LECTURE NOTES IN PHYSICAL OCEANOGRAPHY ODD HENRIK SÆLEN EYVIND AAS 1976 2012 CONTENTS FOREWORD INTRODUCTION 1 EXTENT OF THE OCEANS AND THEIR DIVISIONS 1.1 Distribution of Water and Land..........................................................................1 1.2 Depth Measurements............................................................................................3 1.3 General Features of the Ocean Floor..................................................................5 2 CHEMICAL PROPERTIES OF SEAWATER 2.1 Chemical Composition..........................................................................................1 2.2 Gases in Seawater..................................................................................................4 3 PHYSICAL PROPERTIES OF SEAWATER 3.1 Density and Freezing Point...................................................................................1 3.2 Temperature..........................................................................................................3 3.3 Compressibility......................................................................................................5 3.4 Specific and Latent Heats.....................................................................................5 3.5 Light in the Sea......................................................................................................6 3.6 Sound in the Sea..................................................................................................11 4 INFLUENCE OF ATMOSPHERE ON THE SEA 4.1 Major Wind -
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. -
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. -
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. -
Chapter 5 Water Levels and Flow
253 CHAPTER 5 WATER LEVELS AND FLOW 1. INTRODUCTION The purpose of this chapter is to provide the hydrographer and technical reader the fundamental information required to understand and apply water levels, derived water level products and datums, and water currents to carry out field operations in support of hydrographic surveying and mapping activities. The hydrographer is concerned not only with the elevation of the sea surface, which is affected significantly by tides, but also with the elevation of lake and river surfaces, where tidal phenomena may have little effect. The term ‘tide’ is traditionally accepted and widely used by hydrographers in connection with the instrumentation used to measure the elevation of the water surface, though the term ‘water level’ would be more technically correct. The term ‘current’ similarly is accepted in many areas in connection with tidal currents; however water currents are greatly affected by much more than the tide producing forces. The term ‘flow’ is often used instead of currents. Tidal forces play such a significant role in completing most hydrographic surveys that tide producing forces and fundamental tidal variations are only described in general with appropriate technical references in this chapter. It is important for the hydrographer to understand why tide, water level and water current characteristics vary both over time and spatially so that they are taken fully into account for survey planning and operations which will lead to successful production of accurate surveys and charts. Because procedures and approaches to measuring and applying water levels, tides and currents vary depending upon the country, this chapter covers general principles using documented examples as appropriate for illustration. -
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. -
Tides and the Climate: Some Speculations
FEBRUARY 2007 MUNK AND BILLS 135 Tides and the Climate: Some Speculations WALTER MUNK Scripps Institution of Oceanography, La Jolla, California BRUCE BILLS Scripps Institution of Oceanography, La Jolla, California, and NASA Goddard Space Flight Center, Greenbelt, Maryland (Manuscript received 18 May 2005, in final form 12 January 2006) ABSTRACT The important role of tides in the mixing of the pelagic oceans has been established by recent experiments and analyses. The tide potential is modulated by long-period orbital modulations. Previously, Loder and Garrett found evidence for the 18.6-yr lunar nodal cycle in the sea surface temperatures of shallow seas. In this paper, the possible role of the 41 000-yr variation of the obliquity of the ecliptic is considered. The obliquity modulation of tidal mixing by a few percent and the associated modulation in the meridional overturning circulation (MOC) may play a role comparable to the obliquity modulation of the incoming solar radiation (insolation), a cornerstone of the Milankovic´ theory of ice ages. This speculation involves even more than the usual number of uncertainties found in climate speculations. 1. Introduction et al. 2000). The Hawaii Ocean-Mixing Experiment (HOME), a major experiment along the Hawaiian Is- An early association of tides and climate was based land chain dedicated to tidal mixing, confirmed an en- on energetics. Cold, dense water formed in the North hanced mixing at spring tides and quantified the scat- Atlantic would fill up the global oceans in a few thou- tering of tidal energy from barotropic into baroclinic sand years were it not for downward mixing from the modes over suitable topography. -
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. -
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.