Water and Weather

Chapter Seven: Oceans

• 7.1 Introduction to Oceans

• 7.2 Waves

• 7.3 Shallow Marine Environments

• 7.4 The Ocean Floor

Investigation 7B

• What is the relationship between water depth and wave speed?

Wave Speed

7.2 Waves

• Waves are caused by a disturbance moving forward.

• In the case of water waves, the water moves up and down as the disturbance moves forward.

7.2 Making waves• Waves occur as a repeating pattern of crests

(high point of a wave) and troughs (low point of a wave)

7.2 Making waves• The amplitude of a wave is the distance

between a wave crest or trough and the average level of motion.

• Wavelength is the length of one complete wave.

7.2 More about waves• A wave causes a

circular motion in the water as it passes by but only a small amount of water moves forward slightly as the wave passes.

• Water waves have predictable behaviors.

7.2 More about waves• The seagull and the

dolphin experience the same wave, but the dolphin’s circular path (below the surface) is smaller than the seagull’s.

• There may be no wave motion below the dolphin.

7.2 Wind causes waves• Most ocean waves are caused by friction

between the wind and the ocean surface.

• Fetch is the amount of open water over which wind blows.

7.2 What happens when waves meet

• When waves formed in different places come together, the waves add to and subtract from each other.

7.2 Tsunamis compared to wind waves

• A tsunami is a huge wave made by a large disturbance like an underwater earthquake, landslide, or volcanic eruption.