The Equilibrium Tide

What is the Equilibrium Tide?

The equilibrium tide is the hypothetical tide that would be produced by the lunar and solar tidal forces if the Earth were covered with water to such a depth that the response to these forces is instantaneous. In this idealized case, the Earth would be a perfectly spherical water body with no continents or other obstructions. The equilibrium tide would be a standing wave, with two high tides and two low tides per day. The high tides would be located directly below the moon and on the opposite side of the Earth from the moon, and the low tides would be located between the high tides.

The equilibrium tide is a useful concept for understanding the basic principles of tidal forces, but it is not a realistic representation of the actual tides. The actual tides are influenced by a variety of factors, including the continents, the ocean basins, and the Earth’s rotation. These factors can cause the actual tides to differ significantly from the equilibrium tide.

Here are some of the factors that influence the actual tides:

• Continents: The continents block the flow of water, which can cause the actual tides to differ from the equilibrium tide. For example, the tides in the Atlantic Ocean are different from the tides in the Pacific Ocean because the Atlantic Ocean is surrounded by continents on three sides.
• Ocean basins: The shape of the ocean basins can also affect the tides. For example, the tides in the Bay of Fundy are very high because the Bay of Fundy is a funnel-shaped basin.
• Earth’s rotation: The Earth’s rotation also affects the tides. The Earth’s rotation causes the tides to lag behind the moon and the sun. This lag is responsible for the semi-diurnal tides, which are the two high tides and two low tides per day.

The actual tides are a complex phenomenon that is influenced by a variety of factors. However, the equilibrium tide is a useful concept for understanding the basic principles of tidal forces.

Here is an example of the difference between the equilibrium tide and the actual tide:

The equilibrium tide at the equator would have two high tides and two low tides per day, with the high tides occurring directly below the moon and on the opposite side of the Earth from the moon. However, the actual tides at the equator are diurnal, meaning that there is only one high tide and one low tide per day. This is because the continents block the flow of water and the Earth’s rotation causes the tides to lag behind the moon.

The equilibrium tide is a useful concept for understanding the basic principles of tidal forces, but it is important to remember that the actual tides are more complex and can vary significantly from the equilibrium tide.