Gravity is a strong force that holds everything on Earth steady. It draws us towards the ground, holds the Moon in orbit around the Earth, and even influences the oceans! Did you ever ask yourself why the sea rises and falls or why there are waves and currents? This is all due to gravity. In this blog, we will describe how gravity influences the sea in simple terms.
Tides: The Ocean Moving Up and Down
The most obvious result of gravity’s effect on the sea is tides. Tides are ocean water rising and falling that occur each day. The primary cause of tides is the gravity of the Moon. Although the Moon is really far away, its gravity stretches to Earth’s oceans and pushes the water along.
How Do Tides Work?
- The Moon’s gravity pulls on the water, making a bulge (an area of water higher than the surrounding area) on the side of Earth facing towards the Moon.
- Meanwhile, a second bulge occurs on the other side of Earth due to the combination of Earth’s motion and gravity.
- As the Earth spins, other locations move into the bulge and have high tide (when the water reaches its highest point).
- When an area shifts out of the bulge, it has low tide (when the water is lower).
This high and low tide cycle occurs twice a day. That is why beaches appear different at different times—sometimes there is more sand, and sometimes there is more water!
Spring Tides and Neap Tides
- Spring Tides occur when the Sun, Moon, and Earth are in a line. This causes tides to be stronger and results in very high tides and very low tides.
- Neap Tides occur when the Sun and Moon are at a right angle to one another. This weakens the tides and results in lesser water level changes.
Tides are extremely significant for sea creatures, fishermen, and even ships sailing in the ocean!
Ocean Currents: How Gravity Transports Water Around
Do you ever notice water flowing in the ocean, even without wind? This is due to ocean currents. Ocean currents are similar to rivers in the ocean that transport water around the globe. Gravity assists in forming and regulating these currents.
Types of Ocean Currents
Surface Currents – These are created by the wind, but gravity also has a role in forming them. The Sun warms various regions of the ocean, and gravity assists in transporting the warm water to cold areas.
Deep Ocean Currents – These occur deep beneath the sea and are governed by gravity and density of water. Cold water is denser than warm water, hence gravity forces it down. This gives rise to deep currents that flow slowly throughout the oceans of the world.
These currents assist in the dispersion of heat throughout the planet, warming certain locations and cooling others. They also assist in the movement of sea creatures and delivering food to other areas of the ocean.
Gravity and Earth’s Balance
Gravity doesn’t only act on the ocean; it also balances Earth! Here’s why:
Keeps Oceans in Place – Without gravity, ocean water would drift off into space!
Controls Earth’s Rotation – The Moon’s gravity slows Earth’s rotation, keeping our days and nights at the correct length.
Helps Shape the Planet – Gravity aids in the creation of mountains, valleys, and even the ocean floor!
Conclusion
Gravity is not visible, but it makes a huge difference to the sea. It makes tides, drives ocean currents, and balances Earth. The next time you are at the beach or looking at the waves, remember—because of gravity!
At Anee’s School, one of Mohali and Kharar’s best educational institutions, we enjoy making science fun and simple for students. Keep learning, keep exploring!
