The gravitational interaction between the Moon, the Sun, and the Earth leads to the formation of tidal bulges. When the Moon and the Sun are aligned (during a new moon or a full moon), their gravitational forces combine, resulting in higher high tides known as spring tides. When the Moon and the Sun are at right angles (during a first quarter or third quarter moon), their gravitational forces partially cancel each other out, resulting in lower high tides known as neap tides