Editing Tide (section)

=== Equilibrium ===
The '''equilibrium tide''' is the idealized tide assuming a landless Earth.<ref name="AMS Glossary 2020">{{cite web |title=Equilibrium tide |website=AMS Glossary |date=2020-09-02 |url=http://glossary.ametsoc.org/wiki/Equilibrium_tide |access-date=2020-09-02 |archive-date=2020-08-01 |archive-url=https://web.archive.org/web/20200801165541/http://glossary.ametsoc.org/wiki/Equilibrium_tide |url-status=live }}</ref>
It would produce a tidal bulge in the ocean, elongated towards the attracting body (Moon or Sun).
It is ''not'' caused by the vertical pull nearest or farthest from the body, which is very weak; rather, it is caused by the tangential or [[Traction force|tractive]] tidal force, which is strongest at about 45 degrees from the body, resulting in a horizontal tidal current.{{efn|"The ocean does not produce tides as a direct response to the vertical forces at the bulges. The tidal force is only about 1 ten millionth the size of the gravitational force owing to the Earth's gravity. It is the horizontal component of the tidal force that produces the tidal bulge, causing fluid to converge at the sublunar and antipodal points and move away from the poles, causing a contraction there." (...) "The projection of the tidal force onto the horizontal direction is called the tractive force (see Knauss, Fig. 10.11). This force causes an acceleration of water towards the sublunar and antipodal points, building up water until the pressure gradient force from the bulging sea surface exactly balances the tractive force field."<ref>{{Cite web |first=LuAnne |last=Thompson |author-link=LuAnne Thompson |year=2006 |url=http://faculty.washington.edu/luanne/pages/ocean420/notes/TidesIntro.pdf |title=Physical Processes in the Ocean |access-date=2020-06-27 |archive-date=2020-09-28 |archive-url=https://web.archive.org/web/20200928191813/http://faculty.washington.edu/luanne/pages/ocean420/notes/TidesIntro.pdf |url-status=live }}</ref>}}
{{efn|"While the solar and lunar envelopes are thought of as representing the actual ocean waters, another very important factor must be recognized. The components of the tide-generating forces acting tangentially along the water surface turn out to be the most important. Just as it is easier to slide a bucket of water across a floor rather than to lift it, the horizontal tractive components move the waters toward the points directly beneath and away from the sun or moon far more effectively than the vertical components can lift them. These tractive forces are most responsible for trying to form
the ocean into the symmetrical egg-shaped distensions (the tide potential, the equilibrium tide). They reach their maximums in rings 45° from the points directly beneath and away from the sun or moon."<ref name="Hicks2006">{{cite report |last=Hicks |first=S.D. |title=Understanding Tides |publisher=[[NOAA]] |year=2006 |url=https://tidesandcurrents.noaa.gov/publications/Understanding_Tides_by_Steacy_finalFINAL11_30.pdf |language=en |access-date=2020-09-02 |archive-date=2022-01-20 |archive-url=https://web.archive.org/web/20220120232639/http://www.tidesandcurrents.noaa.gov/publications/Understanding_Tides_by_Steacy_finalFINAL11_30.pdf |url-status=live }}</ref>}}
{{efn|"... the gravitational effect that causes the tides is much too weak to lift the oceans 12 inches vertically away from the earth. It is possible, however, to move the oceans horizontally within the earth's gravitational field. This gathers the oceans toward two points where the height of the water becomes elevated by the converging volume of water."<ref>{{cite book |first=James Greig |last=Mccully |date=2006 |title=Beyond The Moon: A Conversational, Common Sense Guide To Understanding The Tides, World Scientific |publisher=World Scientific |isbn=9789814338189 |url=https://books.google.com/books?id=aKLICgAAQBAJ&q=tractal |via=[[Google Books]] |access-date=2022-01-05 |archive-date=2023-09-16 |archive-url=https://web.archive.org/web/20230916153030/https://books.google.com/books?id=aKLICgAAQBAJ&q=tractal |url-status=live }}</ref>}}<ref name="PBS LearningMedia 2020">{{cite web |title=What Physics Teachers Get Wrong about Tides! - PBS Space Time |website=[[PBS]] LearningMedia |date=2020-06-17 |url=https://www.pbslearningmedia.org/resource/what-physics-teachers-pbs-space-time/what-physics-teachers-pbs-space-time/ |access-date=2020-06-27 |archive-date=2020-10-21 |archive-url=https://web.archive.org/web/20201021020010/https://www.pbslearningmedia.org/resource/what-physics-teachers-pbs-space-time/what-physics-teachers-pbs-space-time/ |url-status=live }}</ref>