by Ian Loft

Created on: March 22, 2007   Last Updated: May 02, 2007

The world's oceans, seas and lakes represent millions of square miles of surface across which air movements ranging from gentle breezes to raging storms create motion and energy that we see as waves. For swimmers and surfers, waves are a source of pleasurable activities however the effects of a giant and destructive tsunami wave can be a source of wide scale damage with loss of life.

Waves, tides and currents all contain energy of motion and potential energy. Waves are actually energy moving across the ocean's surface a common misconception is that waves are moving water. The water in fact only moves in an upward and downward direction as this energy travels across the water surface as evident by observing objects floating out in open water bobbing up and down in one place. Any directional travel observed in a floating object is due to ocean currents not wave motion.

Every wave has a measurable height from trough to peak with a level water line somewhere between. The force and duration of wind determines how high a wave grows, and this is why severe tropical storms (hurricanes, cyclones or typhoons depending on what part of the world you live) often create monster waves and destructive surges as they approach landfall. Sometimes this is made far worse by the accompanying low pressure that causes a huge bubble of water to rise at storm centre and accompany the storm track.

As a wave (energy source) approaches land, the lower part is slowed when it touches the bottom while and the upper section then starts to overtake the wave front. This causes the wave to peak and then curve forward this is what we see from the shoreline when observing crashing foaming wave activity. This is also the point where water actually begins moving. Energy begins to dissipate once the top of the wave collapses into a foaming froth that rumbles toward the shoreline.

Tsunamis are sometimes erroneously called tidal waves when in fact they have nothing to do with tide activity. They are usually the result of underwater earthquakes where large sections of the seafloor suddenly move, by volcanic eruptions or by underwater landslides. The forces of energy compounded by billions of tons in water pressure in the area of sudden displacement translate into energy that creates a series of waves that can travel at speeds from 400 to 600 miles per hour in the open ocean. The largest recorded tsunami occurred following an earthquake in 1737 that generated a wave with a peak more than 50m above sea level striking the North Kurile Islands approximately 700 miles North East of Japan.

Ocean waves are a natural phenomenon generally caused by wind energy interacting with the water surface. They travel great distances and vary in height, energy and shape. On the seashore they are a source of recreation for surfers and swimmers however severe storms or geological activity under the sea surface can sometimes generate very large and destructive waves. Waves are energy in motion.

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