They roll toward the beach, burst into foam, then retreat only to return again. But where do waves come from? It's not the sea "breathing," nor a giant blowing on it... The answer is both simple and surprising.
Illustration image Pixabay
Most of the waves we see on beaches are created... by the wind! When air moves over the water, it slightly rubs against its surface. This friction transfers energy to the water, causing it to ripple. The stronger and longer the wind blows, the taller and more powerful the waves become. It's like blowing on a cup of hot chocolate: at first, small ripples appear, then they grow larger if you blow harder.
But not all waves come from the wind. Some are caused by other natural phenomena. For example:
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Tidal waves, linked to the gravitational pull of the Moon and the Sun, which make the sea level rise and fall.
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Seismic waves, like tsunamis, caused by underwater earthquakes or landslides. These waves are very different: they carry enormous energy and can travel thousands of kilometers (miles).
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Boat waves, created by a ship's passage, which disturbs the water and leaves a wavy trail behind it.
Once formed, waves travel. They can cover long distances, even if the wind that created them has long since stopped. In the open sea, waves resemble rounded hills moving without breaking. But as they approach the shore, the seabed slows their base while the top continues forward: that's when they rise, tilt, and eventually break.
Illustration image Pixabay
Waves also play a crucial role for the planet. They help mix surface water with deeper water, oxygenating the ocean and distributing nutrients essential for marine life. Without this natural churning, many marine species would struggle to survive. They also shape coastlines, eroding some areas and depositing sand elsewhere.
In some parts of the world, waves are so regular and powerful that they become a genuine resource. Engineers are even working on capturing their energy to generate electricity using floating or submerged devices. This "wave energy" could one day help power our homes in a cleaner, more sustainable way.