Earth Science
Water on Earth
Wind Waves
Study Tip
Coastal damage can occur due to the massive amounts of water collected during storm surges.
Ocean Waves
- When the wind blows near an ocean, the energy from the wind is transferred to the water in the form of a wave.
- The energy creates tiny ripples on the surface of the ocean
- The uneven ocean catches more wind, which creates larger waves.
- These waves travel across the ocean out of the area where the wind blows
Study Tip
Coastal damage can occur due to the massive amounts of water collected during storm surges.
- When energy transfers between water molecules, they make circles or ellipses as they bob up and down in place.
The circles show the motion of a water molecule in a wind wave. Wave energy is greatest at the surface and decreases with depth. "A" shows that a water molecule travels in a circular motion in deep water. "B" shows that molecules in shallow water travel in an elliptical path because of the ocean bottom.
Powerful Waves
- Large waves form when winds are strong, blow steadily for a long time, and blows over a long distance.
- If a wave’s base cannot support the height of a wave, the wave then collapses. This usually occurs closer to the coast, but it also happens in the middle of the sea. The energy from the bottom of a wave is lost to friction from the ground, thus causing the top of the wave to continue moving and crash downwards.
- When storm winds push waves and water towards the coast, a storm surge occurs, potentially raising water levels by as much as 7.5 m (25 feet).
Concept Check
- Explain how wind waves are formed and how they move.
- Define a storm surge and explain how they form.
- Explain why waves collapse.
