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Resources Bellringers Chapter Presentation Transparencies Standardized Test Prep Image and Math Focus Bank CNN Videos Visual Concepts
The Movement of Ocean Water Chapter 14 Table of Contents Section 1 Currents Section 2 Currents and Climate Section 3 Waves Section 4 Tides
Chapter 14 Section1 Currents Bellringer Your teacher will read excerpts from Thor Heyerdahl’s Kon-Tiki (1950) or The Ra Expeditions (1971). Look at the large map of the world that shows the different ocean currents and the origination and destination points for Heyerdahl’s voyages. Which currents would he have used to reach his destination? How might you prove your hypothesis? What kind of data would you need?
Chapter 14 Section1 Currents Objectives • Describe surface currents. • List the three factors that control surface currents. • Describe deep currents. • Identify the three factors that form deep currents.
Chapter 14 Section1 Currents One Way to Explore Currents • Ocean water contains streamlike movements of water calledocean currents. • Norwegian explorer Thor Heyerdahl proved his theory that ocean currents influenced human migration by using a raft that was powered only by wind and ocean currents.
Chapter 14 Section1 Currents Surface Currents • Horizontal, streamlike movements of water that occur at or near the surface of the ocean are calledocean currents. • Surface currents are controlled by three factors: global winds, the Coriolis effect, and continental deflections.
Chapter 14 Section1 Currents Surface Currents, continued • Global Winds Winds that blow across the Earth’s surface create surface currents in the ocean. Different winds cause currents to flow in different directions. • The Coriolis Effect is the apparent curving of moving objects from a straight path due to the Earth’s rotation.
Chapter 14 Section1 Currents The Coriolis Effect Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept
Chapter 14 Section1 Currents Surface Currents, continued • Continental Defections When surface currents meet continents, the currents deflect, or change direction.
Chapter 14 Section1 Currents Surface Currents, continued • Taking Temperature Currents are also affected by the temperature of the water in which they form. • The next slide shows Earth’s surface currents. Warm-water currents are shown as red arrows, and cold-water currents are shown as blue arrows.
Chapter 14 Section1 Currents
Chapter 14 Section1 Currents Deep Currents • Streamlike movements of ocean water located far below the surface are calleddeep currents. Deep currents are not controlled by wind. • Deep currents form in parts of the ocean where water density increases. The density of the ocean is affected by temperature and salinity.
Chapter 14 Section1 Currents Deep Currents, continued • Formation and Movement of Deep Currents Differences in water density cause variations in the movement of deep currents.
Chapter 14 Section1 Currents
Chapter 14 Section2 Currents and Climate Bellringer Given the average yearly temperatures for the Scilly Isles in England and Newfoundland in Canada, can you explain why the two locations have very different year-round temperatures? Note their locations on the globe, and use what you know about the movement of ocean currents to support your answer.
Chapter 14 Section2 Currents and Climate Objectives • Explainhow currents affect climate. • Describethe effects of El Niño. • Explainhow scientists study and predict the pattern of El Niño.
Chapter 14 Section2 Currents and Climate Surface Currents and Climate • Warm-Water Currents and Climate Warm-water currents create warmer climates in coastal areas that would otherwise be much cooler.
Chapter 14 Section2 Currents and Climate Surface Currents and Climate, continued • Cold-Water Currents and Climate Cold-water currents keep climates along a coast cooler than the inland climate year-round.
Chapter 14 Section2 Currents and Climate Surface Currents and Climate, continued • Upwelling is the movement of deep, cold, and nutrient-rich water to the surface of the ocean. • The nutrients that are brought to the surface support the growth of plankton. Plankton support larger organisms, such as fish and seabirds. • Upwelling is shown on the next slide.
Chapter 14 Section2 Currents and Climate
Chapter 14 Section2 Currents and Climate Surface Currents and Climate, continued • El Niño is a change in the water temperature in the Pacific Ocean that produces a warm current. • Effects of El NiñoEl Niño alters weather patterns enough to cause disasters, including flash floods, mudslides, and droughts. El Niño also prevents upwelling off the coast of South America.
Chapter 14 Section2 Currents and Climate Surface Currents and Climate, continued • Studying and PredictingEl Niño Learning as much as possible about El Niño is important because of its effects on organisms and land. • To study El Niño, scientist use a network of buoys located along the equator. The buoys collect data about surface temperature, air temperature, currents, and wind.
Chapter 14 Section3 Waves Bellringer Imagine you are floating in the ocean 1 km from shore, which is north of you. There is a surface current flowing east. Are you more likely to travel north with the waves toward the shore or east with the surface current?
Chapter 14 Section3 Waves Objectives • Identifythe parts of a wave. • Explainhow the parts of a wave relate to wave movement. • Describehow ocean waves form and move. • Classifytypes of waves.
Chapter 14 Section3 Waves Anatomy of a Wave • Waves are made up of crests and troughs • A crest is the highest point of a wave. • A trough is the lowest point of a wave.
Chapter 14 Section3 Waves Wave Formation and Movement • Most waves form as wind blows across the water’s surface and transfers energy to the water. • As the energy moves through the water, so do the waves. But the water itself stays behind, rising and falling in circular movements.
Chapter 14 Section3 Waves Formation and Movement of Ocean Waves Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept
w a v e l e n g t h (m) = w a v e s p e e d (m/s) w a v e p e r i o d (s) Chapter 14 Section3 Waves Specifics of Wave Movement • Waves not only come in different sizes but also travel at different speeds. Wave speed is calculated by using the following equation:
Chapter 14 Section3 Waves Specifics of Wave Movement, continued • Wave period is the time between the passage of two wave crests (or troughs) at a fixed point. • The next slide shows how wave period is determined.
Chapter 14 Section3 Waves
Chapter 14 Section3 Waves Types of Waves • Deep-Water Waves and Shallow-Water Waves Deep-water waves are waves that move in water deeper than one-half their wavelength. • When deep-water waves begin to interact with the ocean floor, the waves are called shallow-water waves. This process is illustrated on the next slide.
Chapter 14 Section3 Waves
Chapter 14 Section3 Waves Types of Waves, continued • Shore CurrentsWhen waves crash on the beach head-on, the water they moved through flows back to the ocean underneath new incoming waves. • This movement of water forms a subsurface current that pulls objects out to sea and is called an undertow.
Chapter 14 Section3 Waves Types of Waves, continued • Longshore Currents are water currents that travel near and parallel to the shore line. • Longshore currents form when waves hit the shore at an angle. • Longshore currents transport most of the sediment in beach environments
Chapter 14 Section3 Waves Types of Waves, continued • Open-Ocean Waves Sometimes waves called whitecaps and swells form in the open ocean. • White, foaming waves with very steep crests that break in the open ocean before the waves get close to the shore are called whitecaps. • Rolling waves that move steadily across the ocean are called swells.
Chapter 14 Section3 Waves Types of Waves, continued • Tsunamisare waves that form when a large volume of ocean water is suddenly moved up or down. This movement can be caused by underwater earthquakes, as shown below.
Chapter 14 Section3 Waves Types of Waves, continued • Storm Surgesare local rises in sea level near the shore that are caused by strong winds from a storm. • Winds form a storm surge by blowing water into a big pile under the storm. As the storm moves onto shore, so does the giant mass of water beneath it.
Chapter 14 Section4 Tides Bellringer If the moon had the mass of a golf ball, the sun would have the mass of about 110 school buses! This analogy shows the difference in mass of the moon and the sun. Although the moon is much smaller than the sun is, the moon exerts more influence on Earth’s tides than the sun does. Why do you think this happens?
Chapter 14 Section4 Tides Objectives • Explaintides and their relationship with the Earth, sun, and moon. • Describefour different types of tides. • Analyzethe relationship between tides and coastal land.
Chapter 14 Section4 Tides The Lure of the Moon • The daily changes in the level of ocean water are calledtides. Tides are influenced by the sun and the moon and occur in a variety of cycles. • High Tide and Low Tide How often tides occur and the difference in tidal levels depend on the position of the moon as it revolves around the Earth.
Chapter 14 Section4 Tides The Lure of the Moon, continued • Battle of the Bulge When part of the ocean is directly facing the moon, the water there and the water on the opposite side of Earth bulges toward the moon. The bulges are called high tides. • Water is drawn away from the areas between the high tides, which causes low tides to form.
Chapter 14 Section4 Tides The Lure of the Moon, continued • The figure below shows how the position of the moon affects where high and low tides form.
Chapter 14 Section4 Tides The Lure of the Moon, continued • Timing the Tides Tides occur at different times each day because the Earth rotates more quickly than the moon revolves around the Earth.
Chapter 14 Section4 Tides Tidal Variations • The sun also affects tides. The combined forces of the sun and the moon on Earth result in tidal ranges that vary based on the positions of the three bodies. • Atidal range is the difference between levels of ocean water at high tide and low tide.
Chapter 14 Section4 Tides Tidal Variations, continued • Spring Tides are tides with the larges daily tidal range and occur during new and full moons. During these times, the sun, Earth, and moon are aligned. • Neap Tides are tides with the smallest daily tidal range and occur during the first and third quarters of the moon. During these times, the sun, Earth and moon form a 90º angle.
Chapter 14 Section4 Tides
Chapter 14 Section4 Tides Tides and Topography • In some coastal areas that have narrow inlets, movements of water called tidal bores occur. • A tidal bore is a body of water that rushes up through a narrow bay, estuary, or river channel during the rise of high tide and causes a very sudden tidal rise.
Chapter 14 The Movement of Ocean Water Concept Map Use the terms below to complete the concept map on the next slide.
Chapter 14 The Movement of Ocean Water