(WOE) Waves Lesson

Waves

Waves and tides carry energy from one place to another, and they influence coastlines.

Winds form waves. Without the energy of wind the surface of the ocean would be smooth. Most waves form when winds blowing across the water's surface transmit their energy to the water. A wave is the movement of energy through a body of water.

If ocean waves are caused by wind, how can there be strong waves on calm days?

Waves form where there are winds. Energy from the wind is transferred to the water and then that is transferred to nearby water molecules. The wave moves as a transfer of energy across the sea. Once the wave starts, it doesn't need more wind to keep it going.

Waves transfer energy, and the size of a wave and the distance it travels depends on the amount of energy that it carries. This lesson studies the most familiar waves, those on the ocean's surface.

Building Big Waves

Ocean waves originate from wind blowing – steady winds or high storm winds – over the water. Sometimes these winds are far from where the ocean waves are seen. What factors create the largest ocean waves?

The largest wind waves form when the wind

• is very strong
• blows steadily for a long time
• blows over a long distance

The wind could be strong, but if it gusts for just a short time, large waves won't form.

Wind blowing across the water transfers energy to that water. The energy first creates tiny ripples, which make an uneven surface for the wind to catch so that it may create larger waves. These waves travel across the ocean out of the area where the wind is blowing.

Remember that a wave is a transfer of energy. Do you think the same molecules of water that start out in a wave in the middle of the ocean later arrive at the shore? The molecules are not the same, but the energy is transferred across the ocean.

Properties of Waves

The wavelength of a wave

One of the basic characteristics of a wave is its wavelength. This is the distance from one peak, or crest, to the next. This is the same as the distance from one dip, or trough, to the next.

The amplitude of a wave

The volume of sound, the energy in a water wave, and the brightness of light all depend upon the amplitude of the wave. It is equal to the height of the crest of the wave above the rest position. This is the same as the depth of a trough of a wave below the rest position.

Waves that are close together have a shorter wavelength than waves that are far apart. As waves approach the shore, wavelength decreases and wave height will increase.

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