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What Are the Two Things That Cause Ocean Waves?

The ocean can be different things to different people. If you want to spend a summer day bonding with your family, get close to that special someone or just clear your head, few options are better than heading to the beach and enjoying the waves. However, ocean waves are a phenomenon some beachgoers take for granted. You might expect the explanation for such a powerful force to be convoluted, but waves result from two relatively simple contributing factors.

Factor One: Wind
- Just as wind would try to carry off a sheet, it attempts to lift water as it moves across the ocean's surface.
  
  When wind blows across land, it picks up and carries things, such as dust, leaves or trash. The stronger the wind, the larger and heavier the objects it can transport. When wind blows across the surface of the ocean, it behaves no differently. It attempts to pick up and bring along the water, which contributes to the production of waves. An example of wind's relationship to waves can be found in a region just south of the Indian Ocean, where strong winds consistently blow in one direction. This area is home to some of the biggest waves in the world, reaching an average height of 23 feet.
Factor Two: Gravity
- After wind pulls water upward, gravity causes it to come crashing back down.
  
  As anyone who's ever tried to dump out a children's swimming pool knows, water can be a lot heavier than it looks. While the wind attempts to lift water from the Earth's surface, gravity engages in a valiant battle to pull it back down. Because the weight of the water increases as it accumulates, the wind inevitably loses the fight. The water crashes back down into the ocean with such force that it breaks the surface, plunging deeper than it had been before. This causes an underwater swell that pushes more water up to the surface, creating a wave. As the strength of wind increases, it lifts the water higher; then gravity brings it crashing down harder, creating bigger waves.
Long Journey
- Like the ripples caused by a rock thrown into water, waves move away from the center of the disturbance.
  
  If you've ever thrown a rock into a pond or a lake, you might have noticed that the resulting ripples travel well beyond the point where the rock broke the surface. In the same way, water released from the wind causes the ocean to swell upward, sending ripples or waves that move away from the point of impact and toward the shore. This is why you might see waves when there isn't even a slight breeze. In fact, the tug-of-war between wind and gravity on the water can build such a momentum that waves generated by a storm off the coast of Alaska can easily end up traveling beyond Hawaii.
Benefits of Waves
- Waves are responsible for covering Earth's beaches with sand.
  
  Waves do a lot more than terrorize boaters and provide awesome rides for surfers. The movement along the surface stirs up the water, promoting the exchange of carbon dioxide and oxygen between the ocean and air, and circulates nutrients. Without waves, the ocean would become stagnant, and underwater life wouldn't flourish. Many ocean creatures rely on waves to carry their eggs and larvae to other parts of the ocean, where their chances for survival might be greater. In fact, some only spawn during storms, when they can be certain the waves will be strong.

Nature