From Wikipedia, the free encyclopedia
.^ Tides - The periodic rise and fall of a body of water resulting from gravitational interactions among the sun, moon, and earth.
^ The tides are the regular rising and falling of sea level.- The Physics of Tides 19 September 2009 20:15 UTC www.iit.edu [Source type: FILTERED WITH BAYES]
^ The tidal forces produced by the Moon and Sun, in combination with Earth's rotation, are responsible for the generation of the tides.- Tidal Power 20 September 2009 13:12 UTC www.tqnyc.org [Source type: Reference]
.^ The tides occur with a period of approximately 12 and a half hours and are influenced by the shape of the near-shore bottom .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ These rapid changes occur at exactly the same periods as the tides themselves -- half-daily, daily, etc.- Tides and the Earth's Rotation 19 September 2009 20:15 UTC bowie.gsfc.nasa.gov [Source type: Academic]
^ Semi-diurnal tides have a period of 12 hrs and 25 min, and theoretically have a wavelength of more than half the circumference of Earth.- Ocean Motion : Background :Types of Tides 19 September 2009 20:15 UTC oceanmotion.org [Source type: Academic]
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.^ Low tide: High Tide: .- The Physics of Tides 19 September 2009 20:15 UTC www.iit.edu [Source type: FILTERED WITH BAYES]
^ Frequency of Tides - Most coastal areas, with some exceptions, experience two high tides and two low tides every lunar day.
^ Certain locations have two high and two low tides per day.
.^ This is because at the point right "under" the Moon (the sub-lunar point), the water is at its closest to the Moon, so it experiences stronger gravity and rises.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ At the point right "under" the Moon, the water is closer than the solid Earth; so it is pulled more and rises.- Deltawerken - Tidal physics 20 September 2009 13:12 UTC www.deltawerken.com [Source type: FILTERED WITH BAYES]
^ Here, follow a step-through animation that explains why water rises on the side of the Earth away from the moon.- NOVA | Sinking City of Venice | What Causes the Tides? | PBS 19 September 2009 20:15 UTC www.pbs.org [Source type: FILTERED WITH BAYES]
.^ Because the earth is spinning there will be a bulge on the opposite side of the earth as well.- Why Tides? 19 September 2009 20:15 UTC www.sfgate.com [Source type: FILTERED WITH BAYES]
^ The moon’s gravity pulls more strongly on the side of Earth that faces it and causes the water here to bulge.- How the Moon Affects Tides | Bukisa.com 18 January 2010 0:43 UTC www.bukisa.com [Source type: FILTERED WITH BAYES]
^ On the opposite side of the Earth (the antipodal point), the water is at its farthest from the moon, so it is pulled less; at this point the Earth moves more toward the Moon than the water does—causing that water to "rise" (relative to the Earth) as well.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ In between the sub-lunar and antipodal points, the force on the water is diagonal or transverse to the sub-lunar/antipodal axis (and always towards that axis), resulting in low tide.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The period of tide between high water and low water.- Glossary of Ocean Terms -- Beach-Net 20 September 2009 12:18 UTC www.beach-net.com [Source type: FILTERED WITH BAYES]
^ Some waters are not navigable at low tide.- Puget Sound Shorelines: Beaches - Tides 19 September 2009 20:15 UTC www.ecy.wa.gov [Source type: FILTERED WITH BAYES]
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.^ Tide prediction is important for coastal navigation .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Tide predictions are important for fun and safety .- San Diego Tides 19 September 2009 20:15 UTC www.hribar.com [Source type: General]
^ Because the depth of coastal waters is important for navigation, an average low-water reference is established.
.^ Low tide: High Tide: .- The Physics of Tides 19 September 2009 20:15 UTC www.iit.edu [Source type: FILTERED WITH BAYES]
^ High tide or low tide Lyrics .- BEN HARPER - HIGH TIDE OR LOW TIDE LYRICS 17 September 2009 11:40 UTC www.metrolyrics.com [Source type: General]
^ The strip of seashore that is submerged at high tide and exposed at low tide, the intertidal zone , is an important ecological product of ocean tides (see Intertidal ecology ).- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ Near-open Coast Tide Stations .- USGS Open-File Report 2005-1027, An Operational Mean High Water Datum for Determination of Shoreline Position from Topographic Lidar Data, Data Set and Methods 19 September 2009 20:15 UTC pubs.usgs.gov [Source type: FILTERED WITH BAYES]
^ A tide prediction can differ from the actual sea level that will be observed as a result of the tide.
^ While tides are usually the largest source of short-term sea-level fluctuations, sea levels are also subject to forces such as wind and barometric pressure changes, resulting in storm surge s, especially in shallow seas and near coasts.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ Tidal phenomena are not limited to the oceans, but can occur in other systems whenever a gravitational field that varies in time and space is present.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ More generally, tidal phenomena can occur in other systems besides the ocean, whenever a gravitational field that varies in time and space is present (see Other tides ).- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The whole system was time synchronized such that the pencil tracings of the risings and fallings of the tide could later be scaled to determine the heights and times of various stages of the tides.
.^ For example, the solid part of the Earth is affected by tides.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Solid earth tides .
^ For example, irregularities in the Bay of Fundy and the northern part of the Gulf of California cause tides of exceedingly high ranges, 50 and 30 feet, respectively.
Characteristics
.
^ The tides are the regular rising and falling of sea level.- The Physics of Tides 19 September 2009 20:15 UTC www.iit.edu [Source type: FILTERED WITH BAYES]
^ Low tide: High Tide: .- The Physics of Tides 19 September 2009 20:15 UTC www.iit.edu [Source type: FILTERED WITH BAYES]
^ If so, then you are familiar with its regular rise and fall.- How the Moon Affects Tides | Bukisa.com 18 January 2010 0:43 UTC www.bukisa.com [Source type: FILTERED WITH BAYES]
.^ Which picture shows high tide?
^ So, when this occurs there is little variation between a high and low tide.- Untitled Document 15 September 2009 3:03 UTC www.padillabay.gov [Source type: FILTERED WITH BAYES]
^ Low tide: High Tide: .- The Physics of Tides 19 September 2009 20:15 UTC www.iit.edu [Source type: FILTERED WITH BAYES]
.^ In other regions, such as the Gulf of Mexico, there is only one high tide per day called a diurnal tide, with a period of 24 hr and 50 min.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
- Tide - Facts from the Encyclopedia - Yahoo! Education 18 January 2010 0:43 UTC education.yahoo.com [Source type: FILTERED WITH BAYES]
^ True tidal waves, also known as tide waves, are long-period waves associated with the tide-producing forces of the moon and the sun and which are identified with the rising and falling of the tide.- What is the difference between a tidal wave and a tsunami? 20 September 2009 13:12 UTC www.funtrivia.com [Source type: General]
^ This happens two times a day (this is called a semi-diurnal tide,) unless, in rare cases, a location experiences a diurnal tide which is when there's only one high tide and one low tide a day.
src="http://images-mediawiki-sites.thefullwiki.org/11/1/1/2/91369393828223573.gif" width="300" height="415" class="thumbimage" />
Tide changes proceed via the following stages:
- Sea level rises over several hours, covering the intertidal zone; flood tide.
- The water rises to its highest level, reaching high tide.
- Sea level falls over several hours, revealing the intertidal zone; ebb tide.
- The water stops falling, reaching low tide.
.^ Tides produce oscillating currents known as tidal streams.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Accompanying the vertical rise and fall of water are various horizontal or lateral movements commonly known as tidal currents or tidal streams, which are very different from the common ocean currents.- Tides, Clam Tides, Tide Tables for Long Beach WA, ocean park wa, klipsan beach, leadbetter point, baker bay, ilwaco, seaview, surfside 19 September 2009 20:15 UTC www.funbeach.com [Source type: FILTERED WITH BAYES]
^ Print this section Accompanying the vertical rise and fall of water are various horizontal or lateral movements commonly known as tidal currents or tidal streams, which are very different from the common ocean currents ( see Ocean and Oceanography ).- Tide - MSN Encarta 19 September 2009 20:15 UTC encarta.msn.com [Source type: FILTERED WITH BAYES]
- Tide - MSN Encarta 19 September 2009 20:15 UTC ca.encarta.msn.com [Source type: FILTERED WITH BAYES]
.^ Because tidal currents cease this is also called slack water or slack tide.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ This is not the same as slack water; this is a tidal (vertical) occurence, not a tidal current (horizontal) occurence.
^ This is called slack water .
.^ The tide reverses direction and is said to be turning.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The tide then reverses direction and is said to be turning.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ The arithmetic mean of mean high water and mean low water.
^ Slack water usually occurs near high water and low water.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ How High tides and Low Tides Occur?- How the Moon Affects Tides | Bukisa.com 18 January 2010 0:43 UTC www.bukisa.com [Source type: FILTERED WITH BAYES]
.^ The difference between high tide and low tide is called the tide range.
^ So, when this occurs there is little variation between a high and low tide.- Untitled Document 15 September 2009 3:03 UTC www.padillabay.gov [Source type: FILTERED WITH BAYES]
^ Low tide: High Tide: .- The Physics of Tides 19 September 2009 20:15 UTC www.iit.edu [Source type: FILTERED WITH BAYES]
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.^ In parts of the northern Gulf of Mexico and Southeast Asia, tides have one high and one low water per tidal day.- When does the high tide & low tide happens in the sea? - Yahoo! Answers 18 January 2010 0:43 UTC answers.yahoo.com [Source type: General]
^ The equilibrium tidal theory predicts tides that are semidiurnal, which means two high and two low tides each day.
^ Low tide: High Tide: .- The Physics of Tides 19 September 2009 20:15 UTC www.iit.edu [Source type: FILTERED WITH BAYES]
.^ In a mixed system, it refers to higher high and lower high water and higher low and lower low waters.
^ The difference in height of the two high waters of each tidal day for a mixed or semidiurnal tide.
^ Thus the two high tides a day alternate in maximum heights: lower high (just under three feet), higher high (just over three feet), and again.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ In a mixed system, it refers to higher high and lower high water and higher low and lower low waters.
^ In these tides, we have a higher high-water and lower high-water as well as higher low-water and lower low-water.- Tide - Encyclopedia of Earth 18 January 2010 0:43 UTC www.eoearth.org [Source type: Academic]
^ The arithmetic mean of mean higher high water and mean lower low water.
.^ The daily inequality changes with time and is generally small when the Moon is over the equator .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The daily inequality is not consistent and is generally small when the Moon is over the equator .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ We have seen in § 13 that the potential of the tide-generating force of the moon consists of three terms, one being approximately semi-diurnal, one approximately diurnal, and one varying slowly.
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Tidal constituents
.^ As a result, tidal patterns vary.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Tidal changes are the net result of multiple influences that act over varying periods.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Changing tidal flows by damming a bay or estuary could, however, result in negative impacts on aquatic and shoreline ecosystems, as well as navigation and recreation.- Tidal Energy | Pros for Wave and Tidal Power 20 September 2009 13:12 UTC www.oceanenergycouncil.com [Source type: FILTERED WITH BAYES]
.^ These influences are called tidal constituents.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Careful Fourier data analysis over a nineteen-year period (the National Tidal Datum Epoch in the U.S.) uses frequencies called the tidal harmonic constituents .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The various frequencies of orbital forcing which contribute to tidal variations are called constituents .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ Tides vary on timescales ranging from hours to years.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Tides vary on timescales ranging from hours to years, so to make accurate records tide gauges measure the water level over time at fixed stations which are screened from variations caused by waves shorter than minutes in period.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Spring tides are when the range from high tide to low tide (about a six hour period) is most different.- How does the tidal range change from neap to spring tide and from... 15 September 2009 3:03 UTC www.answerbag.com [Source type: General]
.^ Water depths are measured from this level and recorded on navigational charts.
^ Tides vary on timescales ranging from hours to years, so to make accurate records tide gauges measure the water level over time at fixed stations which are screened from variations caused by waves shorter than minutes in period.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ To make accurate records tide gauges at fixed stations measure the water level over time.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ The gauges ignore variations caused by waves with periods shorter than minutes.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Tides vary on timescales ranging from hours to years, so to make accurate records tide gauges measure the water level over time at fixed stations which are screened from variations caused by waves shorter than minutes in period.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Real amplitudes differ considerably, not only because of variations in ocean depth, and the obstacles to flow caused by the continents, but also because the natural period of wave propagation is of the same order of magnitude as the rotation period: about 30 hours.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ These data are compared to the reference (or datum) level usually called mean sea level.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ A synonym for Sea-level Datum of 1929.
^ These data are compared to the reference (or datum) level usually called mean sea level .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
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Principal lunar semidiurnal constituent
.^ In most locations, tides are semidiurnal .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ In most locations, the largest is the "principal lunar semidiurnal" constituent, also known as the M2 (or M 2 ) tidal constituent.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Smaller lunar elliptic semidiurnal constituent .
.^ The wavelength of the two tidal waves is one-half the circumference of Earth.
^ Its period is about 12 hours and 25.2 minutes, exactly half a tidal lunar day , which is the average time separating one lunar zenith from the next, and thus is the time required for the Earth to rotate once relative to the Moon.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The earth rotates once a day.
.^ This is the constituent tracked by simple tide clock s.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ This is the constituent tracked by simple tide clocks .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ Earth and the Moon are moving in the same direction along their orbit with the Sun.
^ While the earth is turning the moon moves in its orbit.
^ This is because the earth is not only turning on its own axis, but the moon and earth are also rotating on their common barycenter, which means that the moon is not at the same location after 24 hours, but has moved 12.2 degrees to the east, and the earth must rotate another 50 minutes for the moon to come overhead again.
.^ Compare this to the minute hand on a watch crossing the hour hand at 12:00 and then again at about 1:05 (not at 1:00).- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The long opening scene of HAL on the beach is all about process as we watch his daily routine over a period of perhaps hours or even weeks.
^ Its period is about 12 hours and 25.2 minutes, exactly half a tidal lunar day , which is the average time separating one lunar zenith from the next, and thus is the time required for the Earth to rotate once relative to the Moon.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
Range variation: springs and neaps
.^ The equilibrium tidal theory predicts tides that are semidiurnal, which means two high and two low tides each day.
^ So, when this occurs there is little variation between a high and low tide.- Untitled Document 15 September 2009 3:03 UTC www.padillabay.gov [Source type: FILTERED WITH BAYES]
^ That's a difference of two hours between high tide in the two locations.
.^ Notice that this is around the time of the full moon AND when the moon is nearest the Earth.
^ Then explain that a spring tide is when the sun, earth, and moon are aligned (new and full moon).- Untitled Document 15 September 2009 3:03 UTC www.padillabay.gov [Source type: FILTERED WITH BAYES]
^ At full and new phases of the moon the Sun and Moon pull together.
.^ The tide's range is then at its maximum: this is called the spring tide , or just springs .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ This is called spring tide .- OceanLink | Ocean Info - Tides 19 September 2009 20:15 UTC oceanlink.island.net [Source type: FILTERED WITH BAYES]
^ The maximum range of the tide at Aden is 8 ft.
.^ It is not named after the season but, like that word, derives from an earlier meaning of "jump, burst forth, rise" as in a natural spring .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Neap rise " is used to mean the average height between high-water of neap tides and low-water of spring tides.
^ The word is derived from the Greek klima, meaning inclination, and reflects the importance early scholars attributed to the sun's influence.- weather.com - Glossary 15 September 2009 3:03 UTC www.weather.com [Source type: FILTERED WITH BAYES]
.^ When the moon is in first or third quarter, however, it is at right angles to the sun relative to the earth, and the height of the tides is subject to the opposing forces of the sun and moon.- Tides, Clam Tides, Tide Tables for Long Beach WA, ocean park wa, klipsan beach, leadbetter point, baker bay, ilwaco, seaview, surfside 19 September 2009 20:15 UTC www.funbeach.com [Source type: FILTERED WITH BAYES]
^ When the Moon is in first or in third quarter, however, it is at right angles to the Sun relative to Earth, and the height of the tides is subject to the opposing forces of the Sun and Moon.- Tide - MSN Encarta 19 September 2009 20:15 UTC encarta.msn.com [Source type: FILTERED WITH BAYES]
^ It is highest at new moon and full moon and lowest at first and third quarters.
.^ At these points in the lunar cycle, the tide's range is minimum: this is called the neap tide , or neaps .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ At these points in the lunar cycle, the tide's range is minimum: this is called the neap tide, or neaps.- pleamar máxima viva equinoccial 15 September 2009 3:03 UTC www.proz.com [Source type: General]
^ These tides, called neap tides , also occur twice a month.- How the Moon Affects Tides | Bukisa.com 18 January 2010 0:43 UTC www.bukisa.com [Source type: FILTERED WITH BAYES]
.^ These results to high tides that are unusually high and low tides that is unusually low.- How the Moon Affects Tides | Bukisa.com 18 January 2010 0:43 UTC www.bukisa.com [Source type: FILTERED WITH BAYES]
^ High and low tides occur at the same times everywhere on earth.- Untitled Document 15 September 2009 3:03 UTC www.padillabay.gov [Source type: FILTERED WITH BAYES]
^ Note that spring low water is the lowest.- RYA navigation courses - Tides, spring, neap and chart datum: 6 tides. 15 September 2009 3:03 UTC www.sailingissues.com [Source type: FILTERED WITH BAYES]
.^ Neaps result in less extreme tidal conditions.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ During the Moon’s first and last quarters the Sun and Moon act at right angles to each other, and the result is a much reduced tidal range called a “neap tide.” .
.^ There is about a seven day interval between springs and neaps.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The time between spring and neap is approximately 7 days.- RYA navigation courses - Tides, spring, neap and chart datum: 6 tides. 15 September 2009 3:03 UTC www.sailingissues.com [Source type: FILTERED WITH BAYES]
^ Tide day , the interval between the occurrences of two consecutive maxima of the resultant wave at the same place.- tide - definition of tide - synonyms, pronunciation, spelling from Free Dictionary 18 January 2010 0:43 UTC www.freedictionary.org [Source type: FILTERED WITH BAYES]
.^ The changing distance separating the Moon and Earth also affects tide heights.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ High Tide happens when the distance of moon from the earth is low.- When does the high tide & low tide happens in the sea? - Yahoo! Answers 18 January 2010 0:43 UTC answers.yahoo.com [Source type: General]
^ The changing distance of the Moon from the Earth also affects tide heights.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ When the Moon is at perigee the range increases, and when it is at apogee the range shrinks.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Every 7½ lunations (the full cycle from full moon to new to full), perigee coincides with either a new or full moon causing perigean spring tides with the largest tidal range .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ SPRING TIDE A tide of increased range, which occurs about every two weeks when the moon is new or full.- weather.com - Glossary 15 September 2009 3:03 UTC www.weather.com [Source type: FILTERED WITH BAYES]
.^ Spring Tide - Also known as perigean, a tide that occurs during or after a new Moon.- Massachusetts Tide Charts - Main Index 15 September 2009 3:03 UTC www.boatma.com [Source type: General]
^ Every 7½ lunations (the full cycle from full moon to new to full), perigee coincides with either a new or full moon causing perigean spring tides with the largest tidal range .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Full moon madness: last low spring tide of 2008 .- Singapore Celebrates our Reefs!: Full moon madness: last low spring tide of 2008 15 September 2009 3:03 UTC iyor08singapore.blogspot.com [Source type: General]
.^ If a storm happens to be moving onshore at this time, the consequences (property damage, etc.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ If a storm happens to be moving onshore at this time, the consequences (in the form of property damage, etc.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
) can be especially severe.
Semidiurnal range differences
.^ Heights and times of low and high water on each day are published in tide tables.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The equilibrium tidal theory predicts tides that are semidiurnal, which means two high and two low tides each day.
^ So, when this occurs there is little variation between a high and low tide.- Untitled Document 15 September 2009 3:03 UTC www.padillabay.gov [Source type: FILTERED WITH BAYES]
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Bathymetry
.^ The daily inequality changes with time and is generally small when the Moon is over the equator .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The shape of the shoreline and the ocean floor change the way that tides propagate, so there is no simple, general rule for predicting the time of high water from the Moon's position in the sky.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Tides and the environment Would the world be different had there been no tides, no moon?
.^ That's a difference of two hours between high tide in the two locations.
^ The difference in height of the two high waters of each tidal day for a mixed or semidiurnal tide.
^ The difference in height of the two low waters of each tidal day for a mixed or semidiurnal tide.
.^ High and low tides occur at the same times everywhere on earth.- Untitled Document 15 September 2009 3:03 UTC www.padillabay.gov [Source type: FILTERED WITH BAYES]
^ So, when this occurs there is little variation between a high and low tide.- Untitled Document 15 September 2009 3:03 UTC www.padillabay.gov [Source type: FILTERED WITH BAYES]
^ That's a difference of two hours between high tide in the two locations.
.^ That's a difference of two hours between high tide in the two locations.
^ For example, the high tide at Norfolk, Virginia predictably occurs approximately two and a half hours before the moon passes directly overhead.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ How High tides and Low Tides Occur?- How the Moon Affects Tides | Bukisa.com 18 January 2010 0:43 UTC www.bukisa.com [Source type: FILTERED WITH BAYES]
.^ Land masses and ocean basins act as barriers against water moving freely around the globe, and their varied shapes and sizes affect the size of tidal frequencies.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The Prediction of Tides Detailed prediction of ocean tides from theories of classical mechanics and hydrodynamics has not been entirely successful, largely because of complications introduced by the irregular shape of the ocean basins and coastlines.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
^ CONTINENTAL SHELF The zone around the continents extending from the low-water mark seaward, typically ending in steep slope to the depths of the ocean floor.- weather.com - Glossary 15 September 2009 3:03 UTC www.weather.com [Source type: FILTERED WITH BAYES]
.^ As a result, tidal patterns vary.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Since the orbits of the Earth about the Sun, and the Moon about the Earth, are elliptical, tidal amplitudes change somewhat as a result of the varying Earth–Sun and Earth–Moon distances.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Tidal changes are the net result of multiple influences that act over varying periods.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ For example, in the U.S., the East coast has predominantly semi-diurnal tides, as do Europe's Atlantic coasts, while the West coast predominantly has mixed tides.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Nevertheless, Strabo quotes from Posidonius a clear account of the tides on the Atlantic coast of Spain , and connects the tides correctly with the motion of the moon.
^ It is well known that there are strongly marked diurnal and semi-diurnal inequalities of the barometer due to the sun's heat, and they may be described as atmospheric meteorological tides.'
^{[10]}^{[11]}^{[12]}
Other constituents
.^ Factors include gravitational effects due to the Sun, the obliquity (tilt) of the Earth's equator and rotational axis, the inclination of the plane of the lunar orbit and the elliptical shape of the orbits of the Moon and the Earth.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ This accelerates the Moon in its orbit, and decelerates the rotation of the Earth.- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
^ Geological constraints on the Precambrian history of Earth's rotation and the Moon's orbit ".- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
.^ Variations with periods of less than half a day are called harmonic constituents .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Variations with periods of less than half a day are called harmonic constituents.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Conversely, long period constituents cycle over days, months, or years.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ Conversely, long period constituents cycle over days, months, or years.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Long period constituents have periods of days, months, or years.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Nineteen years is preferred because the Earth, Moon and Sun's relative positions repeat almost exactly in the Metonic cycle of 19 years, which is long enough to include the 18.613 year lunar nodal tidal constituent .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
Phase and amplitude
Fig. 4: The
M_{2} tidal constituent.
.^ High water rotates about the amphidromic point once every 12 hours in the direction of rising cotidal lines, and away from ebbing cotidal lines.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ In the M 2 plot above, each cotidal line differs by one hour from its neighbors, and the thicker lines show tides in phase with equilibrium at Greenwich.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ As we have already indicated, the tide in British seas has mainly a progressive character, and the general march of the wave may be exhibited on a chart by what are called cotidal lines.
.^ An arrow on the tidal chart indicates the direction and the average flow speed (usually in knots ) for spring and neap tides.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ There are also nodal points in the ocean where there are no tides, these no-tide places are called amphidromic points.
^ In the open ocean, the tidal currents are rotary, shifting through all directions of the compass in a period matching that of the local tide.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
^{[13]}^{[14]}
.^ Because the M 2 tidal constituent dominates in most locations, the stage or phase of a tide, denoted by the time in hours after high water, is a useful concept.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ In most locations, tides are semidiurnal .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Because tidal currents cease this is also called slack water or slack tide.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ It is also measured in degrees, with 360° per tidal cycle.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Tidal stage is also measured in degrees, with 360° per tidal cycle.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Tides may be semidiurnal (two high waters and two low waters each day), or diurnal (one tidal cycle per day).- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ Lines of constant tidal phase are called cotidal lines .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Lines of constant tidal phase are called cotidal lines , analogous to lines on topographical maps.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The tide heights are expected to follow the tidal force, with a constant amplitude and phase delay for each component.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ Lines of constant tidal phase are called cotidal lines .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ High water is reached simultaneously along the cotidal lines extending from the coast out into the ocean, and cotidal lines (and hence tidal phases) advance along the coast.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ In Europe around 730 AD, the Venerable Bede described how the rising tide on one coast of the British Isles coincided with the fall on the other and described the time progression of high water along the Northumbrian coast.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ Semidiurnal and long phase constituents are measured from high water, diurnal from maximum flood tide.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The bulges represent the crests of the two tidal waves (high tide), directly opposite each other, and the low water areas are the two troughs (low tide).
^ Because the M 2 tidal constituent dominates in most locations, the stage or phase of a tide, denoted by the time in hours after high water, is a useful concept.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ This and the discussion that follows is precisely true only for a single tidal constituent.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Tidal prediction is only possible when accurate observations have been made of the phenomena to be predicted; and the like is true of verification after prediction.
^ While the theorem remains true and the tidal height could be analysed in terms of a single frequency and its harmonics, a large number of significant terms would be required.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ For an ocean in the shape of a circular basin enclosed by a coastline, the cotidal lines point radially inward and must eventually meet at a common point, the amphidromic point.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ For an ocean in the shape of a circular basin enclosed by a coastline, the cotidal lines point radially inward and must eventually meet at a common point, the amphidromic point .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The Prediction of Tides Detailed prediction of ocean tides from theories of classical mechanics and hydrodynamics has not been entirely successful, largely because of complications introduced by the irregular shape of the ocean basins and coastlines.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
.^ The amphidromic point is at once cotidal with high and low waters, which is satisfied by zero tidal motion.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ An amphidromic point is at once cotidal with high and low waters, which is satisfied by zero tidal motion.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ During times of high tide accompanied by high wind and low pressure, as during a hurricane , a tidal surge can occur, causing coastal erosion, flooding, and damage to coastal cities.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
.^ (The rare exception occurs when the tide circles around an island, as it does around New Zealand .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ (The rare exception occurs when the tide encircles an island, as it does around New Zealand and Madagascar.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Either working independently or in groups, ask students to explain in their notebooks the sun and moon's placement when the most extreme high and low tides occur (at the new moon).- Untitled Document 15 September 2009 3:03 UTC www.padillabay.gov [Source type: FILTERED WITH BAYES]
)
.^ Lines of constant tidal phase are called cotidal lines .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The amphidromic point is at once cotidal with high and low waters, which is satisfied by zero tidal motion.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Indeed tidal motion generally lessens moving away from the continental coasts, so that crossing the cotidal lines are contours of constant amplitude (half of the distance between high and low water) which decrease to zero at the amphidromic point.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ High water rotates about the amphidromic point once every 12 hours in the direction of rising cotidal lines, and away from ebbing cotidal lines.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ This is because cotidal lines 180° around the amphidromes are in opposite phase, for example high water across from low water.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ For a 12 hour semidiurnal tide the amphidromic point behaves roughly like a clock face, with the hour hand pointing in the direction of the high water cotidal line, which is directly opposite the low water cotidal line.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ High water rotates about the amphidromic point once every 12 hours in the direction of rising cotidal lines, and away from ebbing cotidal lines.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The amphidromic point is at once cotidal with high and low waters, which is satisfied by zero tidal motion.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ High water rotates about once every 12 hours in the direction of rising cotidal lines, and away from ebbing cotidal lines.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ CYCLONIC FLOW Winds that blow in and around a cyclone , that is counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere.- weather.com - Glossary 15 September 2009 3:03 UTC www.weather.com [Source type: FILTERED WITH BAYES]
^ This rotation is generally clockwise in the southern hemisphere and counterclockwise in the northern hemisphere, and is caused by the Coriolis effect.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The circulation is counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.- weather.com - Glossary 15 September 2009 3:03 UTC www.weather.com [Source type: FILTERED WITH BAYES]
.^ The difference of cotidal phase from the phase of a reference tide is the epoch .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ In the M 2 plot above, each cotidal line differs by one hour from its neighbors, and the thicker lines show tides in phase with equilibrium at Greenwich.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ An obvious fallback then is to have several tidal power generation stations, at locations where the tide phase is different enough so that low power from one station is filled in by high power from another.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ The reference tide is the hypothetical constituent equilibrium tide on a landless Earth measured at 0° longitude, the Greenwich meridian.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ If e denotes the equilibrium height of the tide, it is a function of colatitude and longitude, and may be expanded in a series of spherical surface harmonics e i.
^ Rotate the earth through one full solar day, so that the Greenwich meridian goes around in one full circle.
.^ In the North Atlantic, because the cotidal lines circulate counterclockwise around the amphidromic point, the high tide passes New York harbor approximately an hour ahead of Norfolk harbor.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ These points of no tide were confirmed by measurement in 1840 by Captain Hewett, RN, from careful soundings in the North Sea.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ For example, the high tide arrives in Santa Cruz two hours earlier than it arrives at the Golden Gate Bridge, a mere 60 miles north, even though the moon is over both places at the same time.
.^ South of Cape Hatteras the tidal forces are more complex, and cannot be predicted reliably based on the North Atlantic cotidal lines.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Other advantages over wind and solar include predictable energy output as cyclical tidal patterns allow electricity outputs from ocean energy facilities to be accurately predicted far in advance, providing reliable base power for integration with electrical grids.- Tidal Currents 20 September 2009 13:12 UTC research.nwic.edu [Source type: FILTERED WITH BAYES]
^ Lines of constant tidal phase are called cotidal lines .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
Physics
On the current appearance of the moon, the general tide can be derived
History of tidal physics
.^ Tidal physics was important in the early development of heliocentrism and celestial mechanics , with the existence of two daily tides being explained by the moon's gravity, more precisely explained by universal gravitation, the interaction of the moon's gravity and the sun's gravity explaining the variation of tides.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Two theories help explain tides.
^ The gravity of the moon does create the tides.
.^ Tidal physics was important in the early development of heliocentrism and celestial mechanics , with the existence of two daily tides being explained by the moon's gravity, more precisely explained by universal gravitation, the interaction of the moon's gravity and the sun's gravity explaining the variation of tides.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The gravity of the moon does create the tides.
^ Is the moon more effective than the sun at producing a tide?- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
.^ An early explanation of tides was given by Galileo Galilei in his 1632 Dialogue Concerning the Two Chief World Systems, whose working title was Dialogue on the Tides .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ In a general tide-table 1 References may be given to two papers by G. H. Darwin on this subject, viz.
^ However original any future contribution to the science of the tides may be, it would seem as though it must perforce be based on the work of these two.
.^ However, the resulting theory was incorrect - he attributed the tides to water sloshing due to the earth's movement around the sun, hoping to provide mechanical proof of the earth's movement - and the value of the theory is disputed, as discussed there.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The Prediction of Tides Detailed prediction of ocean tides from theories of classical mechanics and hydrodynamics has not been entirely successful, largely because of complications introduced by the irregular shape of the ocean basins and coastlines.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
^ Neap tide, having the minimum range, occurs during the moon's first and last quarters, when the moon, earth, and sun form a right angle.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
.^ At the same time Johannes Kepler correctly suggested that the moon caused the tides, based upon ancient observation and correlations, which was rejected by Galileo.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The importance of tides for maritime activities has prompted the compilation of tide tables for harbors, which give the time and height of high water and low water based on past observations and corrected for the varying positions of celestial bodies.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
^ During times of high tide accompanied by high wind and low pressure, as during a hurricane , a tidal surge can occur, causing coastal erosion, flooding, and damage to coastal cities.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
.^ It was originally mentioned in Ptolemy 's Tetrabiblos as being derived from ancient observation.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ It will be understood, therefore, that in the following schedules the " argument " is that part of the argument which is derived from theory, the true complete argument being the " argument " -K, where is derived from observation.
.^ Isaac Newton (1642 -1727) was the first person to explain tides scientifically.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Isaac Newton laid the foundations for the mathematical explanation of tides in the Philosophiae Naturalis Principia Mathematica ( 1687 ).- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Isaac Newton laid the foundations of scientific tidal studies with his mathematical explanation of tide-generating forces in the Philosophiae Naturalis Principia Mathematica (1687).- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ His explanation of the tides (and many other phenomena) was published in 1686, in the second volume of the Principia.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Isaac Newton laid the foundations for the mathematical explanation of tides in the Philosophiae Naturalis Principia Mathematica ( 1687 ).- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Isaac Newton laid the foundations of scientific tidal studies with his mathematical explanation of tide-generating forces in the Philosophiae Naturalis Principia Mathematica (1687).- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ Isaac Newton laid the foundations for the mathematical explanation of tides in the Philosophiae Naturalis Principia Mathematica ( 1687 ).- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Tide-generating Force.
^ Isaac Newton laid the foundations of scientific tidal studies with his mathematical explanation of tide-generating forces in the Philosophiae Naturalis Principia Mathematica (1687).- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^{[15]}^{[16]} .^ Tide-generating Force.
^ Isaac Newton laid the foundations of scientific tidal studies with his mathematical explanation of tide-generating forces in the Philosophiae Naturalis Principia Mathematica (1687).- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Based on these developments and the lunar theory of E W Brown , Arthur Thomas Doodson developed and published in 1921 the first modern development of the tide-generating potential in harmonic form: Doodson distinguished 388 tidal frequencies.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ Newton and others before Pierre-Simon Laplace worked with an equilibrium theory, largely concerned with an approximation that describes the tides that would occur in a non-inertial ocean evenly covering the whole Earth.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ An early explanation of tides was given by Galileo Galilei in his 1632 Dialogue Concerning the Two Chief World Systems, whose working title was Dialogue on the Tides .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Maclaurin used Newton’s theory to show that a smooth sphere covered by a sufficiently deep ocean under the tidal force of a single deforming body is a prolate spheroid with major axis directed toward the deforming body.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^{[15]} .^ The other consequence of the tidal acceleration is the deceleration of the rotation of the Earth.- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
^ Tidal locking Tidal force Tides .- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
^ The tide-generating force (or its corresponding potential ) is still relevant to tidal theory, but as an intermediate quantity rather than as a final result; theory has to consider also the Earth's dynamic tidal response to the force, a response that is influenced by bathymetry, Earth's rotation, and other factors.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^{[18]}
.^ In 1738 the Academy of Sciences of Paris offered, as a subject for a prize, the theory of the tides.
^ In 1740, the Académie Royale des Sciences in Paris offered a prize for the best theoretical essay on tides.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Another monograph on tides, treating especially the mathematical developments, is Maurice Levy's La The'orie des marees (Paris, 1898).
.^ Daniel Bernoulli , Leonhard Euler, Colin Maclaurin and Antoine Cavalleri shared the prize.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Daniel Bernoulli , Antoine Cavalleri, Leonhard Euler , and Colin Maclaurin shared the prize.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Daniel Bernoulli , Leonhard Euler , Cohn Maclaurin and Antoine Cavalleri.
.^ Maclaurin used Newton’s theory to show that a smooth sphere covered by a sufficiently deep ocean under the tidal force of a single deforming body is a prolate spheroid (essentially a three dimensional oval) with major axis directed toward the deforming body.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Maclaurin used Newton’s theory to show that a smooth sphere covered by a sufficiently deep ocean under the tidal force of a single deforming body is a prolate spheroid with major axis directed toward the deforming body.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Isaac Newton laid the foundations of scientific tidal studies with his mathematical explanation of tide-generating forces in the Philosophiae Naturalis Principia Mathematica (1687).- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ Maclaurin was the first to write about the Earth's rotational effects on motion.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ If the body is close enough to its primary, this can result in a rotation which is tidally locked to the orbital motion, as in the case of the Earth's moon.- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
^ If other effects were ignored, tidal acceleration would continue until the rotational period of the Earth matched the orbital period of the Moon.- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
.^ Tidal locking Tidal force Tides .- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
^ Euler realized that the tidal force's horizontal component (more than the vertical) drives the tide.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Euler realized that the horizontal component of the tidal force (more than the vertical) drives the tide.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ In 1744 Jean le Rond d'Alembert studied tidal equations for the atmosphere which did not include rotation.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ In 17 4 6 Jean-le-Rond D'Alembert wrote a paper in which he treated the tides of the atmosphere; but this work, like Maclaurin's, is chiefly remarkable for the importance of collateral points.
.^ The first major theoretical formulation for water tides was made by Pierre-Simon Laplace , who formulated a system of partial differential equations relating the horizontal flow to the surface height of the ocean.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ As the tides change, currents must flow to redistribute the ocean's water.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
^ Pierre-Simon Laplace formulated a system of partial differential equations relating the ocean's horizontal flow to its surface height, the first major dynamic theory for water tides.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ Laplace's tidal equations .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The Laplace tidal equations are still in use today.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Laplace tidal equation .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ Laplace's tidal equations .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ William Thomson, 1st Baron Kelvin , rewrote Laplace's equations in terms of vorticity which allowed for solutions describing tidally driven coastally trapped waves, which are known as Kelvin waves .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Laplace tidal equation .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^{[19]} ^{[20]} ^{[21]}
.^ Others including Kelvin and Henri Poincare further developed Laplace's theory.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Laplace's theory without these complications, but the theory is now accessible in H. Lamb's Hydrodynamics and other works of the kind.
.^ Based on these developments and the lunar theory of E W Brown , Arthur Thomas Doodson developed and published in 1921 the first modern development of the tide-generating potential in harmonic form: Doodson distinguished 388 tidal frequencies.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Neap tide, having the minimum range, occurs during the moon's first and last quarters, when the moon, earth, and sun form a right angle.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
^ Isaac Newton laid the foundations of scientific tidal studies with his mathematical explanation of tide-generating forces in the Philosophiae Naturalis Principia Mathematica (1687).- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^{[23]} .^ Some of his methods remain in use.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^{[24]}
Forces
.^ The tidal force produced by a massive object (Moon, hereafter) on a small particle located on or in an extensive body (Earth, hereafter) is the vector difference between the gravitational force exerted by the Moon on the particle, and the gravitational force that would be exerted on the particle if it were located at the Earth's center of mass.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The center of mass of the earth orbits the center of mass of the earth-moon system, held into its orbit by the gravitational pull of the moon.
^ The moon produces two tidal bulges on the earth on a line connecting the centers of the earth and moon.
.^ The derivative of 1/ r 2 , with r = distance to originating body, varies as the inverse cube.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Thus, the tidal force depends not on the strength of the lunar gravitational field, but on its gradient (which falls off approximately as the inverse cube of the distance to the originating gravitational body).- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Thus, the tidal force depends not on the strength of the gravitational field of the Moon, but on its gradient (which falls off approximately as the inverse cube of the distance to the originating gravitational body; see NASA ).- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^{[4]} .^ The gravitational force exerted on the Earth by the Sun is on average 179 times stronger than that exerted on the Earth by the Moon, but because the Sun is on average 389 times farther from the Earth, the gradient of its field is weaker.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The solar gravitational force on the Earth is on average 179 times stronger than the lunar, but because the Sun is on average 389 times farther from the Earth, its field gradient is weaker.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ According to »NASA the lunar tidal force is 2.21 times larger than the solar.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ The solar tidal force is 46% as large as the lunar.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Thus, the tidal force depends not on the strength of the lunar gravitational field, but on its gradient (which falls off approximately as the inverse cube of the distance to the originating gravitational body).- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ More precisely, the lunar tidal acceleration (along the Moon-Earth axis, at the Earth's surface) is about 1.1 × 10 −7 g , while the solar tidal acceleration (along the Sun-Earth axis, at the Earth's surface) is about 0.52 × 10 −7 g , where g is the gravitational acceleration at the Earth's surface.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^{[26]} .^ More precisely, the lunar tidal acceleration (along the Moon-Earth axis, at the Earth's surface) is about 1.1 × 10 −7 g , while the solar tidal acceleration (along the Sun-Earth axis, at the Earth's surface) is about 0.52 × 10 −7 g , where g is the gravitational acceleration at the Earth's surface.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Neap tide, having the minimum range, occurs during the moon's first and last quarters, when the moon, earth, and sun form a right angle.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
^ When the Moon is at first quarter or third quarter, the Sun and Moon are separated by 90° when viewed from the earth, and the forces due to the Sun partially cancel those of the Moon.- pleamar máxima viva equinoccial 15 September 2009 3:03 UTC www.proz.com [Source type: General]
^{[27]} .^ The effect of the other planets is much, much smaller, with the largest being Venus at 0.000113 times that of the Sun.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Venus has the largest effect of the other planets, at 0.000113 times the solar effect.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Nevertheless it must be admitted that the effect produced by solar tidal friction on Jupiter and Saturn has not been nearly so great as on the interior planets.
Fig. . The lunar
gravity differential
field at the Earth's surface is known as the
tide-generating force.
^ The Moon's (or Sun's) gravity differential field at the surface of the earth is known as the Tide Generating Force.- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
^ Earth's surface is known as the tide-generating force .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Graphic of tidal forces; the gravity field is generated by a body to the right.- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
This is the primary mechanism that drives tidal action and explains two equipotential tidal bulges, accounting for two daily high waters.
.^ Tidal forces can also be analyzed this way: each point of the Earth experiences the Moon's radially decreasing gravity differently; they are subject to the tidal force''s of Figure 6, which dominate.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ When the Moon is at first quarter or third quarter, the Sun and Moon are separated by 90° when viewed from the earth, and the forces due to the Sun partially cancel those of the Moon.- pleamar máxima viva equinoccial 15 September 2009 3:03 UTC www.proz.com [Source type: General]
^ Reference: "marea viva" / spring tide Reference information: Around new and full moon when the Sun, Moon and Earth form a line (a condition known as syzygy), the tidal forces due to the Sun reinforce those of the Moon.- pleamar máxima viva equinoccial 15 September 2009 3:03 UTC www.proz.com [Source type: General]
.^ The forcing is only horizontal ( tangent ial).- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Finally, most importantly, only the horizontal components of the tidal forces actually contribute tidal acceleration to the water particles since there is small resistance.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Tidal forces are also responsible for tidal locking and tidal acceleration .- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
.^ They are caused by the gravitational force of one or...- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The actual tidal force on a particle is only about a ten millionth of the force caused by the Earth's gravity.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The tidal force on a particle equals about one ten millionth that of Earth's gravitational force.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ The ocean's surface is closely approximated by an equipotential surface, (ignoring ocean currents) which is commonly referred to as the geoid .- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The ocean's surface is closely approximated by an equipotential surface, (ignoring ocean currents) commonly referred to as the geoid .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The ocean surface moves to adjust to changing tidal equipotential, tending to rise when the tidal potential is high, the part of the Earth nearest the Moon, and the farthest part.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
.^ Since the gravitational force is equal to the potential's gradient , there are no tangential forces on such a surface, and the ocean surface is thus in gravitational equilibrium.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Since the gravitational force is equal to the gradient of the potential, there are no tangential forces on such a surface, and the ocean surface is thus in gravitational equilibrium.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ If the augmentation due to mutual attraction of the water is not included, b i becomes equal to unity; there is no longer any necessity to use spherical harmonic analysis, and we see that if the equation to the surface of an ocean be p= a+S, where S is a function of latitude and longitude , it is in equilibrium under forces due to a potential whose value at the surface of the sphere (where p=a ) is gS. In treating the theory of tidal observation we shall specify the tide-generating forces in this way, and then by means of " the principle of forced vibrations," referred to in § 7 as used by Laplace for discussing the actual oscillations of the sea, we shall pass to the actual tides at the port of observation.
.^ Now consider the effect of external, massive bodies such as the Moon and Sun.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Now consider the effect of massive external bodies such as the Moon and Sun.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Note that for these purposes the only gravitational field considered is the external one; the gravitational field of the body (as shown in the graphic) is not relevant.- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
.^ These bodies have strong gravitational fields that diminish with distance in space and which act to alter the shape of an equipotential surface on the Earth.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The ocean surface moves to adjust to changing tidal equipotential, tending to rise when the tidal potential is high, the part of the Earth nearest the Moon, and the farthest part.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ Note that for these purposes the only gravitational field considered is the external one; the gravitational field of the body (as shown in the graphic) is not relevant.- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
.^ This deformation has a fixed spatial orientation relative to the influencing body.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
.^ The Earth's rotation relative to this shape causes the daily tidal cycle.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ Nineteen years is preferred because the Earth, Moon and Sun's relative positions repeat almost exactly in the Metonic cycle of 19 years, which is long enough to include the 18.613 year lunar nodal tidal constituent .- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ If the body is close enough to its primary, this can result in a rotation which is tidally locked to the orbital motion, as in the case of the Earth's moon.- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
.^ Gravitational forces follow an inverse-square law (force is inversely proportional to the square of the distance), but tidal forces are inversely proportional to the cube of the distance.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ This effect is directly proportional to the mass of the body causing the tide but inversely proportional to the cube of the distance between the bodies.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
^ The retarding force in apogee acts exactly inversely, and diminishes the perigean distance.
.^ The ocean surface moves to adjust to changing tidal equipotential, tending to rise when the tidal potential is high, the part of the Earth nearest the Moon, and the farthest part.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ The ocean surface moves to adjust to changing tidal equipotential, tending to rise when the tidal potential is high, which occurs on the part of the Earth nearest to and furthest from the Moon.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ This is the primary mechanism that drives tidal action and explains two tidal equipotential bulges, accounting for two high tides per day.- Tidal Force and Acceleration 20 September 2009 13:12 UTC www.juliantrubin.com [Source type: FILTERED WITH BAYES]
.^ When the tidal equipotential changes, the ocean surface is no longer aligned with it, so that the apparent direction of the vertical shifts.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The ocean surface moves to adjust to changing tidal equipotential, tending to rise when the tidal potential is high, the part of the Earth nearest the Moon, and the farthest part.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ In the open ocean, the tidal currents are rotary, shifting through all directions of the compass in a period matching that of the local tide.- tide Facts, information, pictures | Encyclopedia.com articles about tide 18 January 2010 0:43 UTC www.encyclopedia.com [Source type: FILTERED WITH BAYES]
.^ The surface then experiences a down slope, in the direction that the equipotential has risen.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ When the tidal equipotential changes, the ocean surface is no longer aligned with it, so that the apparent direction of the vertical shifts.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
Laplace's tidal equations
.^ Ocean depths are much smaller than their horizontal extent.- � Tide Data �"; 18 January 2010 0:43 UTC www.aadet.com [Source type: FILTERED WITH BAYES]
^ The depth of the oceans is much smaller than their horizontal extent; thus, the response to tidal forcing can be modelled using the Laplace tidal equations which incorporate the following features: The vertical (or radial) velocity is negligible, and there is no vertical shear —this is a sheet flow.- Tide encyclopedia topics | Reference.com 18 January 2010 0:43 UTC www.reference.com [Source type: FILTERED WITH BAYES]
^ If this is so in the simple case of an ocean of uniform depth, how much more must it be true of oceans of various depths interrupted by continents?
Thus, the response to tidal forcing can be
modelled using the
Laplace tidal equations which incorporate the following features:
.