The Moon's gravitational pull plays a significant role in the creation of tides on Earth, including the occurrence of high tides on the side opposite to the Moon. This phenomenon is known as the "tidal bulge." Here's a simplified explanation of how it works:
Gravitational attraction: The Moon exerts a gravitational force on the Earth. This force is stronger on the side of the Earth that is closer to the Moon and weaker on the side farther away. The difference in gravitational force across the Earth is referred to as the tidal force.
Tidal force and water: The tidal force affects not only the solid Earth but also the water bodies on the planet, such as oceans and seas. Due to the fluid nature of water, it can be more easily influenced by the tidal force compared to solid land.
Tidal bulges: The tidal force from the Moon creates two tidal bulges on Earth. One bulge is formed on the side of the Earth that faces the Moon, where the gravitational force is strongest. The second bulge is formed on the opposite side, away from the Moon, where the gravitational force is weakest.
Centrifugal force: In addition to the Moon's gravitational force, the rotation of the Earth also plays a role. The rotation generates a centrifugal force, which is an apparent outward force experienced by objects in a rotating reference frame. This centrifugal force is strongest at the Earth's equator and causes a slight bulge around that region.
Combined effect: The tidal bulge on the side facing the Moon is somewhat straightforward to understand—it is due to the Moon's gravitational attraction. However, the tidal bulge on the opposite side is a bit more complex. It arises because the centrifugal force from the Earth's rotation is stronger than the gravitational force there. This creates a second bulge that is a result of the Earth and water being "left behind" as the planet rotates.
As a result, the combined effect of the Moon's gravitational pull and the Earth's rotation leads to two tidal bulges—one facing the Moon and one on the opposite side. The areas with these bulges experience high tides, while the areas between them experience low tides. As the Earth rotates and different regions move through the tidal bulges, tides rise and fall in a regular pattern.
It's worth noting that the Sun also influences tides on Earth, although its effect is less pronounced compared to the Moon due to its greater distance. When the gravitational forces from the Sun and Moon align, such as during full and new moons, we experience higher high tides, known as spring tides. When the gravitational forces partially cancel each other out, during the first and third quarter moons, we experience lower high tides, known as neap tides.