Wave Action

1
Table of Contents

• Wave Action
• Tides
• Ocean Water Chemistry
• Currents and Climate

2
What Is a Wave?
- Wave Action

• Most waves form when winds blowing across the
  waters surface transmit their energy to the
  water.

3
Water Motion Activity
- Wave Action

• Click the Active Art button to open a browser
  window and access Active Art about water motion.

4
How Waves Change Near Shore
- Wave Action

• Near shore, wave height increases and wavelength
  decreases.

5
How Waves Change Near Shore
- Wave Action

• A tsunami is usually caused by an earthquake
  beneath the ocean floor.

6
How Waves Affect the Shore
- Wave Action

• As waves come into shore, water washes up the
  beach at an angle, carrying sand grains. The
  water and sand then run straight back down the
  beach.

7
Using Prior Knowledge
- Wave Action

• Before you read, look at the section headings and
  visuals to see what this section is about. Then
  write what you know about waves in a graphic
  organizer like the one below. As you read, write
  what you learn.

What You Know

1. There are waves in the ocean.
2. Wind causes waves.

What You Learned

1. Waves move energy to the shore.
2. Earthquakes cause tsunamis.

8
Wave Characteristics
- Wave Action

• Click the Video button to watch a movie
  aboutwave characteristics.

9
End of SectionWave Action
10
What Causes Tides?
- Tides

• Tides are caused by the interaction of Earth, the
  moon, and the sun.

11
What Causes Tides?
- Tides

• Spring tides and neap tides are caused by the
  positions of Earth, the sun, and the moon.

12
Plotting Tides
- Tides

• This table lists the highest high tides and the
  lowest low tides for one week at the mouth of the
  Savannah River, where it meets the Atlantic Ocean
  in Georgia.

13
Plotting Tides
- Tides

• Graphing
• Use the data in the table to make a graph. On the
  horizontal axis, mark the days. On the vertical
  axis, mark tide heights ranging from 3.0 to 1.0
  meters. (Hint Mark the negative numbers below
  the horizontal axis.)

• Check students progress as they make their
  graphs. The number 1 should occur at the base of
  the y-axis.

14
Plotting Tides
- Tides

• Graphing
• Plot the tide heights for each day on the graph.
  Connect the high-tide points with one line and
  the low-tide points with another line.

• Make certain that students connect the correct
  points with lines.

15
Plotting Tides
- Tides

• Interpreting Data
• How do the high and low tides change during the
  week?

• During the first six days, the high-tide value
  increases steadily while the low-tide value
  decreases. On day 7, the trends reverse.

16
Plotting Tides
- Tides

• Inferring
• What type of tide might be occurring on day 6?
  Explain.

• Spring tide might be occurring on day 6, when
  there is the greatest difference between high and
  low tides.

17
Previewing Visuals
- Tides

• Before you read, preview Figure 11. Then write
  two questions you have about the diagram in a
  graphic organizer like the one below. As you
  read, answer your questions.

Spring and Neap Tides
Q. When do spring tides occur?
A. During the full and new moon phases
Q. What is a neap tide?
A. A smaller tide that happens at the first- and
third-quarter moons
18
More on Tides
- Tides

• Click the PHSchool.com button for an activity
  about tides.

19
End of SectionTides
20
The Salty Ocean
- Ocean Water Chemistry

• On average, one kilogram of ocean water contains
  about 25 grams of saltsthat is, 35 parts per
  thousand.

21
Calculating Density
- Ocean Water Chemistry

• To calculate the density of a substance, divide
  the mass of the substance by its volume.
• For example, 1 liter (L) of ocean water has a
  mass of 1.03 kilograms (kg).
• Therefore,
• Density 1.03 kg/L

22
Calculating Density
- Ocean Water Chemistry

• Practice Problem
• A 5-liter sample of one type of crude oil has a
  mass of 4.10 kg. What is its density? If this oil
  spilled on the oceans surface, would it sink or
  float? Explain your answer in terms of density.

• The density is 0.82 kg/L (4.10 kg 5.00 L). The
  oil would float on top of the ocean because it is
  less dense than ocean water.

23
Changes With Depth
- Ocean Water Chemistry

• Conditions change as you descend to the ocean
  floor.

24
Asking Questions
- Ocean Water Chemistry

• Before you read, preview the red headings. In a
  graphic organizer like the one below, ask a how
  or what question for each heading. As you read,
  write answers to your questions.

Ocean Water Chemistry
Question
Answer
How salty is the ocean?
Ocean water has an average salt concentration of
35 parts per thousand.
How does the ocean change with depth?
As you descend, the temperature decreases and the
pressure increases.
25
Links on Ocean Water Chemistry
- Ocean Water Chemistry

• Click the SciLinks button for links on ocean
  water chemistry.

26
End of SectionOcean Water Chemistry
27
Surface Currents
- Currents and Climate

• Surface currents, which affect water to a depth
  of several hundred meters, are driven mainly by
  winds.

28
Deep Currents
- Currents and Climate

• Deep currents are caused by differences in the
  density of ocean water.

29
Upwelling
- Currents and Climate

• Upwelling brings up tiny ocean organisms,
  minerals, and other nutrients from the deeper
  layers of the water. Without this motion, the
  surface waters of the open ocean would be very
  scarce in nutrients.

30
Relating Cause and Effect
- Currents and Climate

• As you read, identify the main factors that cause
  surface and deep currents in the oceans. Write
  the information in a graphic organizer like the
  one below.

Cause
Effect
Winds
Surface currents
Differences in ocean-water density
Deep currents
31
Links on Ocean Currents
- Currents and Climate

• Click the SciLinks button for links on ocean
  currents.

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End of SectionCurrents and Climate
33
Graphic Organizer
How Waves Move

Wind creates a ripple on the ocean surface.
Wave travels as a low swell.
Wave touches the bottom in shallow water.
Wavelength decreases and wave height increases.
Wave breaks on shore.
34
End of SectionGraphic Organizer