How are water waves formed?« Back to Questions List

Water waves at the beaches are always a delight to watch. Waves tend to flow continuously across the sea. They may be gentle wiping the shore with a soft touch or a powerful one tearing at the shore. Under normal conditions, they are simply caused by the winds. Apart from wind, natural phenomena like earthquakes and volcanic eruptions would also cause waves.

The local water waves are nothing but the motion of water particles caused by wind. We may think it is the water that moves forward but it is actually less of water and more of energy. Water just acts as the medium that transfers energy. The friction between air and water molecules causes the wind to transfer its energy to the waves.

Wave trains are waves that travel in groups. Depending on the speed of the wind and friction on the surface of water, waves vary in size and strength. Stronger winds cause large waves. Most of the waves are less than 10 feet high measured from the top (crest) to the bottom (trough) between the waves. We may think that water actually moves forward carried by the wind. But what actually happens is that water is stirred up and down in a circular motion. When the wave advances, it moves up the front of the wave, and then slides down the back of the crest, moving in a complete circle from trough to trough.
     

Waves are different from what we call tides. Tides are the rise and fall of ocean that happens twice a day. Tides are caused due to the combined gravitational pull of the moon and earth. These are predictable. On a full moon day or new moon day, the sun and moon are in straight line with the earth and their gravitational pull is combined. The high tides are very high and low tides are very low. The highest and lowest tides occur during this time. These tides are called spring tides.  When the sun and moon are at right angles to the earth, their pulls counteract each other and neap tides occur. When the difference is very small between the lowest and highest tides, the tides are called neap tides.

Why does the moon change in size?

Why is the moon sometimes seen during the day?