On more than one occasion you have heard that the Moon affects the state of the sea and you have wondered how it is possible and what one thing has to do with the other. The short answer is that the moon’s gravity pulls the oceans (and us) towards her. Although it is very far away, it is large enough that its force of gravity is strong enough to carry this phenomenon out.
What are the tides
Tides are the rise and fall of the water level in oceans and even lakes. When the sea level rises to its highest point, we call it high tide. When it falls to its lowest point, it is called low tide. The rise and fall of the tides is known as the tidal cycle.
If there is one high and one low tide each day, it is called the diurnal tide cycle. If there are two high tides and two low tides, it is called a semi-diurnal tidal cycle.. The Moon has the greatest effect on tides, but it is not the only factor that affects them. The Sun and Earth can also affect them.
Tides and the Moon
The Moon affects the tides due to gravity. You may have noticed that every time you jump, you always land on the ground. This is because the Earth’s gravity is pulling you towards it.
The Moon has its own gravity, which pulls the oceans towards it. The Moon’s gravitational pull on us is much weaker than Earth’s, so we don’t really notice it, but we can see the Moon’s effect on liquid water in the oceans. The oceans are pulled slightly towards the Moon’s gravity, causing a bulge or high tide on the side of the Earth closest to the Moon.
The effect of the Earth
If the Moon causes a high tide on one side of the Earth, what causes the high tide on the other side? The Earth is spinning, that’s why we have night and day. The spin of the Earth means that another high tide occurs on the opposite side of the Earth to the Moon.. These two high tides separate the water from the rest of the oceans, causing two low tides between the high tides.
The Sun, like the Moon and Earth, also has its own gravity that can affect the tides. Even if Sun is much larger than the Moon and has more gravity, it is also much further away, which means that its attraction on the tides is less than half that of the Moon.
However, it still works. When the Sun and Moon are in line with Earth (when a full moon or new moon occurs), their combined gravity causes very high tides (and very low tides), known as «spring tides.»
When the Sun and Moon are at right angles to each other (during a waxing or waning moon), the Sun helps cancel the pull of the Moon’s gravity, causing lower high tides and higher than average low tides, known like «neap tide». Therefore, the Moon affects the tides due to gravity, but the Sun’s gravity and the Earth’s spin also change their behavior.