The effect of the sun on tides

Transcription

1 Name: Read each article. Then, create the following thinking maps to go with the articles: rticle 1: Ocean Tides reate a OULE ULE MP that compares and contrasts the effect of the sun on tides and the effect of the moon on tides. ( ULES S NEEE) The effect of the sun on tides The effect of the moon on tides Tree Map: reate a TREE MP that classifies the four different types of tides. e sure to ESRIE each tide briefly underneath. The first one is done as an example. Types of Tides Spring Tide Higher than normal high tide, affected by the sun-during new moon or full moon

2 rticle 2: The Ocean onveyor elt reate a FLOW MP that details the steps of how an ocean freezes. reate a IRLE MP that defines what currents are, using information from the article. First, Next, urrents Finally, Then, Fill in the TREE MP with information from the article to support/describe/elaborate on each branch URRENTS TYPES OF URRENTS USES OF URRENTS IMPORTNE OF URRENTS EXMPLES OF URRENTS

3 Name: Read each article. Then, create the following thinking maps to go with the articles: rticle 3: The ig One by sea and not by land reate a OULE ULE MP that compares and contrasts the San ndreas Fault with the ascadia Fault. ULES TO THE MP. San ndreas Fault ascadia Fault Tree Map: reate a TREE MP that explains why the ascadia Fault is dangerous. USE INFORMTION FROM RTILE. Reasons why ascadia Fault is angerous reate a ULE MP describing Tsunamis. JETIVES ONLY. Each bubble should have ONE word, a describing word (Example given) IG Tsunamis

4 rticle 4: Ridges and Trenches reate a OULE ULE MP that compares and contrasts RIGES and TRENHES. ( ULES S NEEE) RIGES TRENHES Tree Map: reate a TREE MP that classifies the four different types of tides. e sure to ESRIE each tide briefly underneath. The first one is done as an example. Evidence of How Mid-Ocean Ridges Form

5 6E3 tmosphere, Water ycle, Waves, and urrents Ocean Tides Lexile 960L 1 The gritty sand oozes between your toes as you stroll along the beach. The gentle lapping of the waves lulls you into a peaceful state. The ocean water appears to stretch its cool fingers farther up onto the shore than it did earlier in the day. Is it your imagination or is the water level rising? 2 Well, you may feel better knowing that it is not your mind playing tricks on you. Throughout each day, the ocean water rises and falls at different times. This movement of water is known as a tide. tide is a change in water level at the shoreline; it is being caused by the pull of gravity between Earth and the Moon and Earth and the Sun. uring each 24-hour period, the beach will experience two high tides and two low tides in most places around the world. Periodically, the beach will also experience a spring tide and a neap tide. 3 How does the gravity between the Moon and Earth cause a tide? Each day, the beach can expect a high tide, a low tide, another high tide, and then another low tide. etween each of these tides is approximately six hours. This is important to know because each quarter turn of Earth takes six hours. Earth will make four quarter turns in a 24-hour period. With each turn, the Earth and the Moon will be in different positions. These positions determine if it is a high or low tide. These tides are a direct effect of the Moon's gravity tugging on the water on Earth. 4 The Moon's gravity has a powerful effect on Earth's waters. In fact, it is far more powerful than the Sun's effect. Why, you ask? It is because the Moon is closer to Earth than the Sun. The Moon pulls the water that is on the side of Earth facing the Moon toward itself in a big bulge. t the exact same time, on the side of Earth that is facing away from the Moon, another bulge is forming. These two places will experience high tides. The opposite places on Earth, which are not facing toward or away from the Moon, will experience low tides. s Earth keeps making quarter turns, the tides change from high to low and low to high. 1

6 6E3 tmosphere, Water ycle, Waves, and urrents 5 How does the Sun affect the ocean tides? s mentioned before, the Sun has less of an effect on the tides. However, the gravitational tug of the Sun can increase a high tide by making it rise higher than normal. This is known as a spring tide. spring tide has absolutely nothing to do with the season spring. spring tide happens when the Moon is either in its new moon or full moon phase. The Moon, Sun, and Earth line up perfectly with one another. This allows their gravitational pull on the ocean to work together making the high tide rise higher. 6 neap tide is the opposite of a spring tide. neap tide is a lower than normal high tide. t the same time, there is also a higher than normal low tide. This happens as the Moon enters a first and last quarter moon phase. t this time, the Sun and the Moon are in positions that form a right angle to one another. The gravitational pull of the Sun pulls water away from the bulge formed by the Moon at high tide. The water moves toward the places that are having low tides. This results in a low high tide and a high low tide. 7 In a 24-hour period, a beach will have two high tides and two low tides. When the Moon is new or full, it will line up with the Sun and Earth causing a spring tide. When the Moon and the Sun form a right angle to one another, there will be a neap tide. The next time you visit a beach, pay attention to the water level on the shoreline. You might just experience a high or low tide yourself. s you do, remember that the gravitational pull of the Moon is what is causing the ocean tides. 2

7 6E3 tmosphere, Water ycle, Waves, and urrents 1 Which statement best describes what an ocean tide is? change in water level that makes a high tide higher change in water level at the shoreline that is being caused by the gravitational pull of the Moon change in water level at the shoreline that is being caused by the gravitational pull of the Sun change in water level that makes a low tide lower 2 What effect does the Sun have on the ocean tides? The Sun does not have an effect on the ocean tides because it is too far away. The Sun warms the water causing it to rise. The gravitational pull of the Sun causes spring and neap tides. The gravitational pull of the Sun's gravity is more powerful than the Moon's. 3

8 6E3 tmosphere, Water ycle, Waves, and urrents 3 uring a spring tide, the Moon is either in its new moon or full moon phase. What effect does this have on an ocean tide? The Moon, Sun, and Earth line up perfectly with one another, allowing their gravitational pulls to work together and making the high tide rise higher. The Moon and Sun are positioned at a right angle to one another causing a lower than normal high tide. The Sun warms the water causing it to rise. In most places, the beach will experience two high tides and two low tides. spring tide only happens during the springtime. 4 How does the gravity between the Moon and Earth cause the tides to rise and fall? The position of the Sun interferes with the Moon's gravity. uring each quarter turn that Earth makes, the Moon and Earth line up in different positions allowing for the high and low tides. Earth makes four quarter turns each day causing spring and neap tides. The gravity of the Moon is stronger at night than during the day. 4

9 6E3 tmosphere, Water ycle, Waves, and urrents 5 What is the main point of paragraph 3? Solar flares affect the tides. Tides are not affected by the Moon's orbit. The neap tide is the opposite of the spring tide. Gravity between the Moon and Earth causes different tide levels. 5

10 6E3 Earth s Water The Ocean onveyor elt Lexile 700L 1 Water in the ocean is always moving. Waves break the surface. urrents move in the shallows and in the depths. urrents near the surface are mainly caused by the winds and tides. eep water currents run on a different engine. 2 urrents run through all of the Earth s oceans. They are important for several reasons. The currents help keep global temperatures even. They move energy around the oceans. Otherwise, the equator and tropics would get too hot. The poles would get too cold. While deep water currents do play a part in energy transfer, this is mainly done by surface currents. These are currents in the top 100 meters of the ocean. Their main driving force is the wind. They flow quickly and form giant circles. One example is the ntarctic ircumpolar urrent, which forms a giant ring around the continent of ntarctica. 3 urrents also cycle nutrients through the ocean. Water near the surface is rich in oxygen. eep waters are rich in nutrients. When sea creatures die, they sink to the ocean bed. They decay and release nutrients into the deep water. There must be a way to mix and exchange the two. In fact, there is a slow global deep water current. Wallace roecker is a noted oceanographer. roecker named this the ocean conveyor belt. 4 eep ocean currents are caused by thermohaline circulation. What does this mean? Well, thermo- means temperature. nd -haline means salt. ut how do temperature and salt cause currents? The linking factor is density. 5 ensity is a physical property of all materials. It is the measure of how much mass the material has for a standard particular volume, generally 1 cm 3. Whether something sinks or floats on a liquid is based on its density. more dense substance, either liquid or solid, will sink to the bottom. less dense substance will be found on the top. Water is more dense as a liquid than as a solid. This is why ice floats. Liquid water can vary in density. s long as it remains a liquid, water gets more dense as it gets colder. lso, water s properties change based on how much salt is dissolved in it. The measure of salt in a water sample is called salinity. Water gets more dense as its salinity goes up. 1

11 6E3 Earth s Water 6 There are three special places on Earth where conditions are right to pump the ocean conveyor belt. Two are in the North tlantic Ocean. The other is the Weddell Sea off the coast of ntarctica. ll three locations lie near either the north or south rctic ircle. On the map at the top of this passage, these locations are labeled deep water formation. onditions are right in these places to make water very, very dense. It will sink to the bottom of the ocean. ut how does this happen? We will focus on the Weddell Sea for the answer. Remember that a similar process happens in the North tlantic to form deep water. 7 uring the winter months, air temperatures in ntarctica are very cold. reas surrounding ntarctica get very little sunlight for much of the winter. Moving closer to the South Pole, some areas get no sunlight at all for weeks. Very cold winds from the interior of the ntarctic continent blow away from the South Pole. t the Weddell Sea, local geography funnels these winds over the surface of the water. The Weddell Sea is fringed year round by ice sheets. onditions are much colder in the winter. Sheets of ice form rapidly. Much of the sea has seasonal ice coverage. This rapid ice formation is one piece of the puzzle. The strong icy winds are another. 8 When ice forms from salt water, an interesting thing happens. The ice that forms is pure water. The salt gets left behind. (This works as long as some of the water remains liquid.) In the Weddell Sea, there is rapid formation of lots of pack ice. Much of the salt is left behind. This leads to water with very high salinity. There is another interesting property of water. s the salinity of a water sample goes up, its freezing point goes down. This means that very salty water will stay liquid below the freezing point of fresh water. The icy winds cool the water, often to -1 (30 F). The winds turn this high salinity water into the coldest, densest water in Earth s oceans. It sinks. This forms the ntarctic ottom Water. The other two locations form slightly less dense North tlantic eep Water. 9 The sinking of the newly formed deep water pushes the water from previous years. This drives the slowly moving ocean conveyor belt. The ntarctic ottom Water forms a current that travels around the continent of ntarctica. The North tlantic eep Water slowly creeps south to join these currents. Portions of the giant current break off. They travel along the bottom of the Indian and the Pacific Oceans. The deep currents are shown in blue in the image at the top of this passage. Finally, they will return to the surface. These upwellings bring nutrients up to replenish surface water. Scientists think deep water may take between 600 and 1,000 years to return to the surface. 2

12 6E3 Earth s Water 1 What is the driving force of the deep water ocean conveyor belt? Winds push the deep water into the Pacific and Indian Oceans. Gravity from the Moon pulls the deep water toward the equator. The spinning of the Earth makes the deep water current run in circular paths. Very cold temperatures create very dense water that pushes the deep current along. 2 What is the meaning of circumpolar in paragraph 2? ircular path around the pole Wind-blown current old and salty Sinking 3

13 6E3 Earth s Water Examine the map below. Use it to answer questions 3 and 4. 3 ased on the information in the passage, which location on the map above marks the Weddell Sea? 4 Which location on the map above is a source of North tlantic eep Water? 4

14 6E3 Earth s Water 5 Which of these characteristics will produce the most dense water? High salinity, high temperature High salinity, low temperature Low salinity, high temperature Low salinity, low temperature 5

15 "The ig One" by sea and not by land y Los ngeles Times, adapted by Newsela staff on Word ount 629 Surfer Lee Johnson emerges from the water at San Onofre State each, alif., with the twin domes from the San Onofre Nuclear Generating Station in the distance. Officials have said the plant can sustain a 7.0 quake but not the 9.0 that struck Japan in Photo: Mark oster/los ngeles Times/MT LOS NGELES Scientists worry that a strong earthquake off the coast of alifornia could do major damage to the West oast. Earthquakes on land can cause a lot of damage. ut earthquakes in the ocean have their own dangers. These earthquakes can cause a tsunami, a huge wave that rushes into coastal cities. The ascadia fault line, 700 miles off the coast of Northern alifornia, could produce a tsunami that would heavily damage the West oast, scientists say. giant tsunami along the West oast would wash away towns, destroy U.S. Highway 101 and cause $70 billion in damage. The wave could destroy bridges, knock down power lines, and cut communication systems like phones or Internet. It s possible that people would only have 15 minutes to escape. s many as 10,000 people could die.

16 Early Warning System Officials in alifornia, Oregon and Washington are now making plans to prepare for an earthquake and tsunami. They hope to learn lessons from a 2011 disaster in Japan. 9.0 earthquake there created a huge tsunami that flooded coastal areas. That tsunami took people by surprise. It killed more than 10,000 and left more than 300,000 homeless. It also damaged a nuclear power plant. meltdown at the plant spread dangerous radiation in the area. Researchers on the West oast hope to save lives by quickly spotting a tsunami and warning local citizens. They hope that new tsunami detectors deep under the ocean can provide early warnings. Predicting a tsunami s strength is important to saving lives. Japanese scientists did not realize how big their tsunami was. Local people were not prepared, and many lost their lives. It s very important to have correct information, said Vasily Titov, head of the U.S. National Oceanic and tmospheric dministration's (NO) enter for Tsunami Research. Escape To High Ground To escape a tsunami, people must get to high ground such as a hill or mountain. ut in flat areas, there is nowhere to go. Safety officials must build high ground. One idea is buildings with roofs that can protect people from a tsunami. One of these at a school in Washington will protect 1,000 people with a high wall. Officials have also discussed building man-made hills. Each hill could hold as many as 800 people. alifornia is famous for the San ndreas fault. This fault runs through the heart of the state. It produced the famously scary 1906 San Francisco earthquake. The 1906 quake killed more than 3,000 people. Scientists now think that the ascadia fault is more dangerous than they thought. The ascadia fault is made up of three tectonic plates that are pushing against each other. The most powerful earthquakes in the last 10 years in alifornia were caused by ascadia. Scientists had believed that the ascadia fault could only produce a 7.5 earthquake. ut they now believe that it could create an enormous 9.0 quake. Like Rubber and The ascadia fault is dangerous for two reasons. First, it is very long.

17 Second, it is an area where two huge tectonic plates are being pushed under the evenlarger North merican plate. The smaller plates push under little by little, dragging the North merican plate down with them. ut the North merican plate is old and strong, and it won t be pulled down forever. Once every couple hundred years, the North merican plate snaps back upward like a rubber band, creating a strong earthquake. On March 16, a small earthquake caused by the ascadia fault erupted 50 miles off the coast, causing light shaking. No injuries or damages were reported. The West oast was spared this time, but scientists still wonder when The ig One will hit. It could be today. It could be 100 years from now, U.S. Geological Survey seismologist avid Oppenheimer said.

18 Quiz 1 What are two MIN ideas of the article? Fill in the blank. Scientists are worried that a strong tsunami on the fault line will cause a serious tsunami; we can prepare by _. () () () () ascadia; setting up tsunami warning systems and and building on high ground. San ndreas; moving people to different cities that are safer and less prone to earthquakes. Japanese; setting up sensors underwater to detect earthquakes and tsunamis. Oregon; fundraising to pay for protective barriers and also to pay for rebuilding destroyed areas. 2 Which of the following accurately summarizes the section "Like Rubber and"? () () () () The San ndreas fault is like a rubber band because the North merican plate gets pushed down and snaps back up every couple hundred years. The ascadia fault is like a rubber band because the North merican plate gets pushed down and snaps back up every couple hundred years. The ascadia fault is like a rubber band because there are a bunch of tectonic plates knocking into one another constantly like bumper cars. The ascadia fault is like a rubber band because it always produces the world's largest earthquakes every 1,000 years. 3 ccording to the article, what is the relationship between earthquakes and tsunamis? () () () () Tsunamis typically occur in costal areas, and earthquakes occur in landfilled areas. Earthquakes only occur in where there are mountains, and tsunamis occur where warm water and air mix. n earthquake that occurs in the ocean may cause a huge wave, called a tsunami, that can destroy coastal cities. n earthquake that occurs on land may cause a huge tsunami that can destroy marine life far away from the shore.

19 4 Why are officials in alifornia, Oregon and Washington interested in a 2011 disaster in Japan? () () The Japanese experienced a tsunami caused by an earthquake, which is precisely what the West oast is preparing for. Researchers on the West oast hope to avoid what happened to the Japanese by installing tsunami detectors. () oth option and. () Natural disasters that happen in Japan are always used by scientists to predict natural disasters in other countries.

20 nswer Key 1 What are two MIN ideas of the article? Fill in the blank. Scientists are worried that a strong tsunami on the fault line will cause a serious tsunami; we can prepare by _. () () () () ascadia; setting up tsunami warning systems and and building on high ground. San ndreas; moving people to different cities that are safer and less prone to earthquakes. Japanese; setting up sensors underwater to detect earthquakes and tsunamis. Oregon; fundraising to pay for protective barriers and also to pay for rebuilding destroyed areas. 2 Which of the following accurately summarizes the section "Like Rubber and"? () () () () The San ndreas fault is like a rubber band because the North merican plate gets pushed down and snaps back up every couple hundred years. The ascadia fault is like a rubber band because the North merican plate gets pushed down and snaps back up every couple hundred years. The ascadia fault is like a rubber band because there are a bunch of tectonic plates knocking into one another constantly like bumper cars. The ascadia fault is like a rubber band because it always produces the world's largest earthquakes every 1,000 years. 3 ccording to the article, what is the relationship between earthquakes and tsunamis? () () () () Tsunamis typically occur in costal areas, and earthquakes occur in landfilled areas. Earthquakes only occur in where there are mountains, and tsunamis occur where warm water and air mix. n earthquake that occurs in the ocean may cause a huge wave, called a tsunami, that can destroy coastal cities. n earthquake that occurs on land may cause a huge tsunami that can destroy marine life far away from the shore.

21 4 Why are officials in alifornia, Oregon and Washington interested in a 2011 disaster in Japan? () () The Japanese experienced a tsunami caused by an earthquake, which is precisely what the West oast is preparing for. Researchers on the West oast hope to avoid what happened to the Japanese by installing tsunami detectors. () oth option and. () Natural disasters that happen in Japan are always used by scientists to predict natural disasters in other countries.

22 6E3 Ocean Topography Ridges and Trenches Lexile 760L 1 More than 100 years ago, geologist lfred Wegener made an interesting connection. Wegener realized that the coastlines of merica and frica fit together like a jigsaw puzzle. lso, similar fossils are found on both continents. He proposed that the continents had once been joined. They had later drifted apart. He did not know how this continental drift happened. New technology was required to discover the underwater ridges and trenches that make continental drift possible. 2 Most scientific discoveries combine observation and inspiration. In the 1950s, Marie Tharp and ruce Heezen led a team of geologists. They made the first scientific map of the ocean floor. They sailed around the ocean. They made many measurements of water depths. They found a vast mountain range running along the middle of the tlantic Ocean. They named it the Mid-tlantic Ridge. t first they thought that this ridge was unique to the tlantic Ocean. Later they found that ridges are in most oceans. These scientists discovered that mid-ocean ridges existed. They still did not know how they formed. 3 Later studies by other scientists provided clues to how mid-ocean ridges form. Geologists measured the magnetic properties of the ocean floor near the ridges. They found a pattern of stripes. Rocks record the magnetic orientation of Earth at the time they are formed. Earth s magnetic field flips orientation every few million years. Therefore, the stripes alternate. Importantly, the stripes are the same on both sides of the ridge. This suggests that rock moves away from the ridge in both directions. Geologists found the age of rocks at different distances from the ridge. Their data showed that younger rock is closer to the ridge. Older rocks are found farther from the ridge. The last piece of evidence is from pictures of ridges. The ridges show lava flows like those seen on volcanoes on land. These observations led scientists to propose that seafloor spreading is part of continental drift. This is also known as plate tectonics. The theory of plate tectonics explains how Earth looked in the distant past. It explains many modern features. Plate tectonics allows us to predict how Earth might look in the distant future. 4 We now know that the seafloor itself moves. It carries the continents with it. The entire crust of Earth is divided into about 15 plates. These plates move on top of a semisolid mantle. The movements are powered by convection currents. New crust forms at the mid- 1

23 6E3 Ocean Topography ocean ridges. It moves away from the ridges in both directions. The plates are moving away from each other. Therefore, these areas are called divergent plate boundaries. etween 2 cm and 20 cm of new crust are formed at each mid-ocean ridge. fissure in Earth s crust allows magma to erupt; it then cools into new crust. Eruptions and small earthquakes are common along the 65,000 km of mid-ocean ridges encircling Earth. The formation of new crust increases the distance between continents. It makes some oceans bigger. 5 New crust is being added continually at mid-ocean ridges. oesn t that mean that Earth is always getting bigger? If addition of new crust were the only process at work, the answer would be yes. Some scientists do think Earth is actually getting bigger. However, most scientists think Earth stays pretty much the same size. To keep Earth at the same size, crust must be destroyed at about the same rate as it is created. In fact, old crust is destroyed at convergent boundaries. Old crust goes back into the mantle through the process of subduction. How does this work? ontinents are carried along the moving plates. Some plates collide and break apart. These movements cause earthquakes and volcanic activity. 6 Here is where ocean trenches become important. Ocean trenches are also called submarine valleys. They are the deepest parts of the ocean. Scientists must use special submarines to explore the trenches. The water pressure is very high at these extreme depths. The pressure can be equal to a car sitting on top of one square centimeter. The Marianas Trench in the western Pacific Ocean reaches depths up to 11 km. Mount Everest is the tallest mountain on Earth. Mount Everest could fit into the trench with 2 km to spare! These trenches form where two tectonic plates come together. This is usually a continental plate and an oceanic plate. The oceanic plate is denser. It gets pushed under the continental plate. The oceanic plate goes back into the mantle and melts. This process often creates earthquakes or hot spots that cause volcanoes. perfect example of this is an area known as the Pacific Ring of Fire. This large area forms a horseshoe shape around the Pacific Ocean. It runs along the eastern coasts of Indonesia and Japan, north to Russia. Then it extends to the west coast of North merica, all the way to South merica. It has the largest number of active volcanoes and destructive earthquakes on the planet. Most of this activity is due to subduction of the seafloor under tectonic plates at the continents edges. 7 The basics of the theory have been worked out over the last century. Research is still discovering new aspects. Two large earthquakes were recorded in the Indian Ocean in These earthquakes suggest that the ustralian and Indian plates are separating. The actual separation will probably take several million years. Large earthquakes, however, might become more common. Geologists have studied earthquake waves passing through the crust near the alifornia coast. ata show that a chunk of an ocean plate is still stuck to the bottom of the continental plate. Subduction may therefore not always be smooth. Research also shows that Earth may not be the only planet with plate tectonics. large canyon system on Mars seems to have fault lines. Fault lines often mark plate boundaries. Several long lines of volcanoes suggest that a tectonic plate moved slowly over a hot spot. 2

24 6E3 Ocean Topography 1 Which of the following pieces of evidence does not explain how mid-ocean ridges are formed? The rocks closer to the ridge are younger than those farther away. Mid-ocean ridges are found on the bottom of most oceans. The magnetic orientation of rocks is symmetrical on either side of mid-ocean ridges. Pictures of ridges show evidence of lava flows. 2 Which of the following correctly defines a divergent boundary? small part of Earth s mantle location of high volcanic activity location where tectonic plates move apart section of crust that moves as a unit 3

25 6E3 Ocean Topography 3 Which of the following is LEST NEESSRY for plate tectonics? solid core inside the planet. semisolid mantle. onvection currents in the mantle. crust divided into plates. 4 Which of the following statements regarding a convergent plate boundary between continental crust and oceanic crust is not true? Earthquakes are common at the boundary. Mountains are formed. Hot spots that may create volcanoes are formed. Oceanic crust changes into continents. 4

26 6E3 Ocean Topography 5 Subduction of ocean crust happens at a mid-oceanic ridge. far from tectonic plate boundaries. inside volcanoes of the Ring of Fire. in deep ocean trenches. 6 What evidence suggests that the ustralian and Indian plates are separating? The formation of a new oceanic ridge Recent large magnitude earthquakes The way earthquake waves travel through the area The presence of a string of volcanoes 5