Figure 14.7: Ocean waves transfer energy through the water over great distances. ( 34 )Waves
Awaveis a disturbance that transfers energy through matter or empty space. Sound waves
move through the air, earthquakes send powerful waves through solid earth, spacecraft radio
waves travel across millions of miles through the vacuum of empty space, and ocean waves
move through water. All of these types of waves are able to transfer energy over great
distances. The size of a wave and the distance it travels depends on the amount of energy
that the wave carries.
The most familiar waves occur on the ocean’s surface. It is upon these waves that surfers
play and boogie boarders ride. These waves are mostly created by the wind. There are three
factors wind that determine the size of the wave: 1) the speed of the wind, 2) the distance
over which the wind has blown, and 3) the length of time that the wind has blown. The
greater each of these factors, the bigger the wave.
Waves can be measured by their amplitude, a distance measured vertically from thecrest
(the top of the wave) to thetrough(the bottom of the wave). They can also be measured
by theirwavelength, which is the horizontal distance between crests (Figure14.8). When
wind blows across the water surface, energy is transferred to the water. The transfer of that
energy may create tiny ripples that disappear when the wind dies down, or it may create
larger waves that continue until they reach the shore. Most waves reach the shore.
Scientists sometimes describe waves by measuring the speed of a wave. A wave’s speed
is determined by measuring the time it takes for one wavelength to pass by. Interestingly,