What makes waves?
Quick answer from Eartha
Wind is the main wave-maker! As wind blows over the ocean, it pushes and ripples the water's surface. The stronger and longer the wind blows, the bigger the waves get. Waves travel across the sea until they reach the shore, where they curl over and crash onto the sand.
The longer story
Most ocean waves start with wind. As wind blows across the water's surface, it drags and pushes on it, creating small ripples that grow into bigger waves the longer and harder the wind blows.
Out in the open ocean, waves are really just energy moving through the water, not the water itself travelling far. Picture a rope shaken up and down: the wave shape moves along it, but the rope stays roughly in place.
When a wave finally reaches shallow water near the beach, it slows down at the bottom while the top keeps moving fast. This makes the wave rise up, curl over and break onto the sand as white foam.
Not all waves come from wind. Huge waves called tsunamis can be caused by underwater earthquakes, and some very large swells travel across the ocean from storms far away, arriving as gentle rolling waves days later.
Try this at home: Make waves in a tub
- Fill a shallow tub or tray with water.
- Blow gently and steadily across the surface with your breath.
- Watch the ripples form, then blow harder and see how the waves change.
Words to know
- Energy
- The push or force that makes things move, like wind moving water.
- Swell
- Smooth, rolling waves that have travelled a long way from a storm.
For grown-ups: what is my child learning here?
Age band: 5-8
Curriculum link: Australian Curriculum v9 Science, AC9SFI07 - forces and movement
The concept: Explores wind energy transferring into water movement.
More classroom ideas are on our teachers page, and safety notes for families are on for parents.
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