Relative Effects of the Sun and Moon on Tides

Tides are the regular rise and fall of sea levels caused by the gravitational forces exerted by the Moon and the Sun, and the Earth’s rotation.
There are two main types of tides, spring tides and neap tides, determined by the relative positions of the Sun, Earth and Moon.

The Moon is the primary influence on Earth’s tides.
Tidal forces are the result of the gravitational attraction between two bodies decreasing with distance. This causes a gravitational pull that is stronger on the side of the Earth closest to the Moon and weaker on the side farthest from the Moon.
This difference in gravitational force causes the Earth to stretch slightly along the line joining the Earth and Moon, creating two bulges: a high tide bulge on the side of the Earth closest to the Moon, and a low tide bulge on the side farthest from the Moon.
As the Earth rotates, different areas move into these regions of high tide and low tide, creating the tidal cycle.

The Sun also plays a role in tides, though a lesser one compared to the Moon due to its much greater distance, despite having a stronger overall gravitational pull.
Similar to the Moon, the differential gravitational force exerted by the Sun creates its own tidal bulge.

When the Sun, Earth, and Moon are arranged in a line during a new moon or full moon, their gravitational forces combine to create spring tides. These tides have the largest range between low and high tides.
Neap tides occur during the first and third quarter moon, when the Sun and Moon are at right angles to each other relative to the Earth. Their gravitational forces partly cancel each other out, resulting in smaller differences between low and high tides.

The interaction between the solar and lunar tidal bulges can lead to variations in the tide’s magnitude and frequency over the course of a month and the year.
Understanding these tidal patterns and their causations is crucial for many activities including shipping, fishing, and coastal construction.