Low tide vs High tide: What are Tides?
What are tides? Have you ever noticed the tides changing from low tide to high tide? If you try to spend a whole day on the beach, you may have observed the tides are different in the morning and in the afternoon.
High tides and low tides occur twice in a day, but do you know why?
This week, find out "how" tides work and "why" it only occurs in oceans and seas.
How does the moon affect the tides and how do tides work?
Tides are the recurring rise and fall of the planet's oceans. Tides change because of two factors, the rotation of the Earth and the gravitational forces A gravitational force is a force generated by the gravity of the sun, moon, and Earth itself. The moon is the primary cause of the tides changing every day, but the sun also has its part.
You need to know that: A Tidal force is the gravitational force exerted by two objects orbiting each other.
The moon's gravitational force draws the water closer to the moon, creating a bulge on the same side of the Earth.
At the opposite side of the bulge closest to the moon is another bulge caused by inertia.
How Many Tides in a Day
A cycle of two low tides and two high tides a day occur in most coastlines in the world.
How does this happen? Because water is a liquid, so a flowing matter, inertia keeps it going in a straight line.
Try to see it for yourself! When you tilt a glass of water, you may observe how the top of the water stays in a straight line.
The combination of the gravity and inertia forms the two bulges on opposite sides of the Earth in a straight line.
As the Earth rotates, your region will pass through these bulges every day. The bulges are what you experience as high tides. If your region is not in the bulge, you will experience low tide.
Neap Tides and Spring Tides: What Types of Tides?
The sun also causes a small bulge (called a solar tide), but since the sun is farther away than the moon, its tidal force is only half as strong. The alignment of the sun, moon, and Earth create two kinds of tides, the spring tides and neap tides.
Neap tides are lower high tides and higher low tides than average. This happens when the sun and moon are perpendicular (90° apart) from each other. Neap tides occur seven days after spring tides. This is a period of balanced tides.
Spring tides happen when both sun and moon align, making lunar tides and solar tides combine. The phenomenon leads to extremely high tides and extreme low tides. Spring tides occur during a new moon, full moon, and solar eclipse.
Why are there no tides in rivers, lakes, and ponds?
Tides only occur in the ocean because it is the largest and only body of water that is free to move all around the planet. Water in lakes, rivers, and ponds do experience a tidal force, but the tides are microscopic. These bodies of water are also not big enough to be moved by gravity, thus unable to create waves.
On bigger lakes, tides are masked by a phenomenon called Seiche. Seiches are standing waves that often occur in an enclosed body of water. It is caused by strong winds and quick changes in atmospheric pressure that pushes the water from one end to the other.
The World's Highest Tides
The Bay of Fundy tides is known for its extremely high tidal range (the change between a low tide and the succeeding high tide). It is located in Canada, between the provinces of New Brunswick and Nova Scotia.
160 milliard (160 billion in the short system) of seawater metric tonnes enter and exit the Bay of Fundy twice a day, this is more than all the world's freshwater rivers combined! The average tidal range of all oceans is 1 meter (~3 feet), but the Bay of Fundy can reach up to 16 meters (~52 feet).
The causes of such tides are the large amount of water from the Atlantic Ocean and its unique shape and size. The Bay of Fundy is a famous tourist attraction in Nova Scotia, and one of the world's greatest natural wonders.
What are Tides Researches and References
If you want to know more about what are tides, take a look at our references below.
Below are few links we have used as references, images we use are from Paul Cowell and Patrice Laborda, Draw is from Marrielle Ferrer and Patrice Laborda, montage with oversized moon is from Patrice Laborda on a Paul Cowell Photo,Tidal Wave is from Free Stock Photos.
- What causes tides
- Wikipedia Tide
- What causes the tides
- Bay of Fundy Tides: The Highest Tides in the World!
- Gravity, Inertia, and the Two Bulges
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Thanks for reading, and if you wish, see you next week!
The Research and Media Team at Scotty's.