Spring and Neap Tides

Many are familiar with the concept that the Moon creates high and low tides on Earth, but few know that the Sun also plays a role in the process. Tides are formed from the gravitational forces of the Sun and Moon pulling on the Earth differently in different places due to variations in distance. The closest part of the Earth to the Sun/Moon is tugged more so than the center of the Earth. This causes the Earth to bulge slightly, in the same way a rubber band does when tugged on one side. The Moon is the much more dominant party in tidal affairs, despite its inferior gravitational force. This is because it is much closer to the Earth, so the differences created in its gravitational fields are much more pronounced compared to the Sun. Nonetheless, the Sun’s tidal force is still felt, especially when it directly contrasts or works alongside that of the Moon.

Spring tides occur when the Sun and Moon work in perfect harmony with each other to produce higher high tides and lower low tides. Such occurs when the Moon is in the new or full phase and the Sun and Moon are both tugging on Earth in the same directional axis. Their efforts become added and a conjuncted, more powerful force is created. If the spring tide occurs one of the equinoxes the tide becomes even more polarized as the Sun forms a straighter line than usual with Moon and Earth at the equator. Neap tides on the other hand refer to the weaker tides which occur when the Sun and Moon are working against each other. This happens when the Moon forms a ninety degree angle with the Sun relative to the Earth (first and third quarter phases). Neap tides occur about 7 days after a spring tide.