Waves at shallow water facts for kids
Shallow water waves are special ocean waves that happen when a wave moves from deep water into a shallow area, like near a beach. This happens when the wave's length (the distance from one wave crest to the next) is much bigger than how deep the water is. When waves reach these shallow spots, the bottom of the ocean starts to affect how the water moves.
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How Waves Change in Shallow Water
In deep water, water particles move in circles as a wave passes. But when a wave enters shallow water, the ocean floor gets in the way. This stops the circular motion, especially at the bottom of the wave.
As the water gets shallower, the wave starts to change. It gets taller and steeper. Imagine a smooth hill turning into a sharp, tall wall of water. This is because the front of the wave slows down due to friction with the seabed, while the back of the wave keeps moving at its original speed. This causes the wave to "pile up" on itself.
When Waves Break
Eventually, the wave becomes too tall and steep to support itself. It then "breaks," which means the top of the wave curls over and crashes down. This is what you see as white foam near the shore. When a wave breaks, the water moves very powerfully and chaotically. It's no longer a smooth flow but a turbulent mix of water and air.
Impact on the Coastline
The powerful, turbulent water from breaking waves has a big effect on the ocean floor and the shoreline. It can pick up and move sand, rocks, and other materials. This process is called erosion. Erosion can change the shape of beaches and coastlines over time. It can wear away land and move sediment from one place to another.
Shallow Water Waves and Tsunamis
One of the most powerful examples of shallow water waves is a tsunami. Tsunamis are giant ocean waves often caused by underwater earthquakes. In the deep ocean, a tsunami might not look very big, but it travels incredibly fast. As a tsunami approaches the coast and moves into shallow water, it behaves just like other shallow water waves. It slows down, but its height increases dramatically, turning into a massive, destructive wall of water that can cause huge damage to coastal areas.