What Causes Tides

Sandstone cliffs adjacent to the ocean at high tide.
Sandstone cliffs along a rocky beach adjacent to the ocean with water removed due to a low tide.
Sandstone cliffs next to the ocean. The water is high against the cliffs with a +7.3 ft. high tide.
A rocky beach next to a body of water at a low tide of -1.5ft.
People walking along a rocky shore. Three areas are defined with the low zone closest to the ocean, the middle zone, and the high or Splash zone closest to the cliffs. A zero tide line is drawn between the high and middle zones.
A rocky beach next to a body of water at a low tide of -1.5ft. and a second photo at high tide of 7.3ft.
On the left, a drawing of the earth with tidal bulges on the sides. Next to that is a drawing of the earth Earth with the sun to the right and the moon to the top, indicating Neap tides. Below that is another drawing with the moon and sun in a straight line with the earth, indicating Spring tides.
A drawing with several points of the moon's rotation around the earth.
The solid and dashed circles represent near-equatorial cross-sections through the earth, containing the plane of the Moon’s orbit around the barycenter(G). Points E1, E2, E3 and M1, M2, M3 are corresponding positions of the centers of mass of the Earth and Moon respectively.
A drawing of the earth with the moon to the right. Dashed lines between the two show the gravitational forces.
A drawing of a man holding a ball on a string swings it in a circle around him.
Gravitational force and centripetal force create RESULTANT FORCES – which generate the tides – those resultant forces become more horizontal at steeper angles – so the farther you get from the equator the greater the tidal range.
Top picture shows Earth with tidal bulges on sides with sun and moon in alignement with earth indicating Spring tides. Bottom picture shows Earth with tidal bulges on the top and bottom with sun and moon at righ angles, indicating Neap tides.
Constructive interference on a spring tide – the sun and moon align Destructive interference during neap tides or quarter moon phases…. Wash each other out a bit.
A globe with bulges on the sides.The equator is shown with a red arrow pointing to the right indicating the rotation of the earth. A dashed circle slightly larger than the earth indicates Mean sea level.
Graph with blue squiggly line showing two and two low tides for a single day. One high tide is higher and one is lower.
Graph with blue squiggly line showing two and two low tides for a single day. One high tide is higher and one is lower.
A map of the world with a closeup of the Bay of Fundy in Nova Scotia, Canada.
Nova Scotia, Canada – Bay of Fundy – extreme tidal ranges – most extreme spring tide – tidal range of 56 feet.
A comparison of a large ship sitting in water at high tide and then on the ocean bottom at low tide. Also a comparison of an island with steep cliffs sitting in the water at high tide and then at low tide with the water removed.

 

Last revised 12-Sep-20