The Sun, Water Cycle, and Climate

Transcription

1 The Sun, Water Cycle, and Climate From the series Water Smart Written and Produced by Alan Sealls, B.S., M.S. Distributed by FAX

2 This video is the exclusive property of the copyright holder. Copying, transmitting, or reproducing in any form, or by any means, without prior written permission from the copyright holder is prohibited (Title 17, U.S. Code Sections 501 and 506) Alan Sealls

3 Table of Contents Introduction Links to Curriculum Standards Summary of the Program Instructional Notes Pre-Test Student Preparation Student Objectives Introducing the Program View the Program Discussion Questions Description of Blackline Masters Answer Key Extended Learning Activities Script of Narration This video is closed captioned. The purchase of this program entitles the user to the right to reproduce or duplicate, in whole or in part, this teacher s guide and the blackline master handouts that accompany it for the purpose of teaching in conjunction with this program, The Sun, Water Cycle, and Climate. This right is restricted only for use with this program. Any reproduction or duplication in whole or in part of this guide and the blackline master handouts for any purpose other than for use with this program is prohibited.

4 CLASSROOM/LIBRARY CLEARANCE NOTICE This program is for instructional use. The cost of each program includes public performance rights as long as no admission charge is made. Public performance rights are defined as viewing of a video in the course of face-toface teaching activities in a classroom, library, or similar setting devoted to instruction. Closed Circuit Rights are included as a part of the public performance rights as long as closed-circuit transmission is restricted to a single campus. For multiple locations, call your United Learning representative. Television/Cable/Satellite Rights are available. Call your United Learning representative for details. Duplication Rights are available if requested in large quantities. Call your United Learning representative for details. Quantity Discounts are available for large purchases. Call your United Learning representative for information and pricing. Discounts, and some special services, are not applicable outside the United States. Your suggestions and recommendations are welcome. Feel free at any time to call United Learning at

5 The Sun, Water Cycle, and Climate from the series Water Smart Grades 3-8 Viewing Time: 15 minutes INTRODUCTION Water Smart is a unit of study comprised of four programs. Spectacular video examples and supporting material make the study of water come alive to students. Every program's teacher's guide lists water-related projects that students at even the lowest grades can undertake, while each guide suggests advanced study topics and projects. The series is an entire "course" in the courses of water in our world and in our lives. Each program stands alone in approaching the various facets of water on Earth. These colorful, educational, and entertaining programs highlight the crucial role water plays in life and how kids can help to conserve and protect it. The Water Smart series is written and produced by Alan Sealls, an award-winning meteorologist recognized nationally in science textbooks, CD-ROMs, and educational TV programs. Alan Sealls holds B.S. and M.S. degrees in Meteorology. He has worked for WGN-TV, CNN, and other TV stations around the United States. The Sun, Water Cycle, and Climate shows us how the sun produces heat to drive the water cycle. It's made clear that the water cycle continues in the absence of sunlight or heat. We learn how the two components of climate- temperature and precipitation, are influenced by the water cycle. By the program conclusion, kids are able to explain how the water cycle and climate are dependent on the sun. 1

6 LINKS TO CURRICULUM STANDARDS The Sun, Water Cycle, and Climate correlates to the following science standards: National Science Education Standards, K-4 Science as Inquiry CONTENT STANDARD A: Abilities necessary to do scientific inquiry Understanding about scientific inquiry Physical Science CONTENT STANDARD B: Properties of objects and materials Life Science CONTENT STANDARD C: The characteristics of organisms Organisms and environments Earth and Space Science CONTENT STANDARD D: Properties of earth materials Objects in the sky Changes in earth and sky Science and Technology CONTENT STANDARD E: Abilities of technological design Science in Personal and Social Perspectives CONTENT STANDARD F: Personal health 2

7 National Science Education Standards, 5-8 Science as Inquiry CONTENT STANDARD A: Abilities necessary to do scientific inquiry Understandings about scientific inquiry Physical Science CONTENT STANDARD B: Properties and changes of properties in matter Motions and forces Earth and Space Science CONTENT STANDARD D: Structure of the earth system Science and Technology CONTENT STANDARD E: Abilities of technological design Science in Personal and Social Perspectives CONTENT STANDARD F: Personal health SUMMARY OF PROGRAM The Sun, Water Cycle, and Climate presents the sun as the source of energy for Earth, driving the water cycle. This program covers the fundamental phases of the water cycle but goes beyond precipitation, evaporation, and condensation. We recognize how plants assist in evaporation via transpiration. We also see how ice "evaporates" in the process of sublimation. Runoff is presented as a link between precipitation and evaporation as water flows into lakes and oceans. The heat capacity of oceans and large water bodies is shown to be a climate control, all at a level that kids comprehend. Excellent visuals and animations illustrate unique forms of condensation in dew and frost. Students become aware that the water cycle is far-reaching, never-ending, and crucial to life in plants and people. 3

8 At the program conclusion, a true/false quiz assesses students understanding. Teachers will be able to further illustrate components of the water cycle using the eight experiments and demonstrations provided. Measuring rainfall, for example, allows practice in recording and charting data. In addition, twelve unique Internet links will lead to further study by kids, and additional lesson plan ideas for the classroom. INSTRUCTIONAL NOTES Before presenting this lesson to your students, we suggest that you preview the program and review the guide and accompanying Blackline Master activities in order to familiarize yourself with their content. As you review the materials presented in this guide, you may find it necessary to make some changes, additions, or deletions to meet the specific needs of your class. We encourage you to do so; for only by tailoring this program to your class will they obtain the maximum instructional benefits afforded by the materials. PRE-TEST Pre-Test is an assessment tool intended to gauge student comprehension of the objectives prior to viewing the program. Explain to the students that they are not expected to get all answers correct, but they are expected to try their best. You can remind them that these are key concepts that they should focus on while watching the program. STUDENT PREPARATION Find information on the Internet or from your local county cooperative extension on how much rain or snow falls in your community each year. Have students guess the number of inches. Have students list what happens to the rain or snow after it hits the ground. Have them describe where they've seen it go. 4

9 Likely answers are that the snow melts, and like rain, it flows into drains or downhill into streams. Some kids may note that the water also seeps into the ground. Speculate what would happen if several years of below-average rain or snow occur. Look for articles describing the effects of drought. Likewisem look for current event articles of the effects of too much precipitation. Use Blackline Master #5 to introduce vocabulary relevant to water on the Earth. Have students look up and define each word. Any one of the Blackline experiments will help raise the interest of students as you start the program. STUDENT OBJECTIVES Upon completion of the program and follow-up activities, students should be able to: Identify the source of energy for the water cycle. Explain unique forms of condensation. Describe the role of plants in the water cycle. Illustrate the large heat capacity of water. Discuss how runoff fits into the water cycle. Describe the phases of water. Define transpiration, percolation, evaporation, and condensation. Discuss the role of clouds in influencing temperature. Outline the water cycle. Describe how the water cycle provides fresh water. Predict relative rates of evaporation for water. INTRODUCING THE PROGRAM Engaging the students before they view the program is key in maximizing its impact. Start by simulating the water cycle. Demonstrate how water in a pot will evaporate when heated. Hold another pot or pan above the steam from the evaporating 5

10 water to see it condense and fall back as droplets. Draw parallels between evaporation, condensation, precipitation, and runoff. Ask students to describe what they think controls the water cycle, and how the water cycle might control the climate for a city. It is best to identify misconceptions and misinformation about the water cycle before the lesson. Pre-Test or discussion questions may be used to help accomplish this. A video quiz corresponding to Blackline Master #4 is at the program conclusion. You may choose to pause the program for a longer period of time between questions to allow for answers or discussion. VIEW THE PROGRAM The program runs 15 minutes. Blackline Master #4, Video Quiz, corresponds to the ten true/false questions at the end of the program. DISCUSSION QUESTIONS These questions appear on Blackline Master #3, they can be duplicated and distributed to the class. Following the program, you may find it helpful to discuss the key concepts as a class. You may choose to use these questions to begin a discussion prior to viewing the program. Avoid answering questions directly; ask the students higher-level questions allowing them to discover the answer as a group. Feel free to add or delete questions to suit the needs of your class. Answers are included in the answer key of this guide. 6

11 DESCRIPTION OF BLACKLINE MASTERS Blackline Master #1, Pre-Test, is an assessment tool intended to gauge student comprehension of the objectives prior to participating in the program. Blackline Master #2, Post-Test, is an assessment tool to be administered after viewing the program and completing additional activities. The results of this assessment can be compared to the results of Pre-Test to determine the change in student comprehension before and after participation in this lesson. Blackline Master #3, Discussion Questions, can be included before viewing the program to help assess the students comprehension and misgivings before beginning the lesson. Give them to the whole class or to small groups to research and report back to the class. Blackline Master #4, Video Quiz, is intended to reinforce the key concepts of the program immediately following the presentation of the program. The quiz can be used as a tool to outline salient points before viewing the program Blackline Master #5, Vocabulary List, will reinforce words used within the program and provide related vocabulary not used in the program. From the list, you may have students look up words to define, write essays, poetry, or short stories. Blackline Master #6, Word Search #1, is a fun way to learn vocabulary. Blackline Master #7, Word Search #2, is also a fun way to learn vocabulary. Blackline Master #8, Crossword Puzzle #1, is another fun way to learn vocabulary. 7

12 Blackline Master #9, Crossword Puzzle #2, is a fun way to learn vocabulary. Blackline Master #10, Crossword Puzzle #3, is also a fun way to learn vocabulary. Blackline Master #11, Fact Sheet Quiz, offers trivia along with website links to further information that kids may use to develop a game show. Blackline Master #12, Experiment #1: Make the Water Cycle, is a clear illustration of the components of the water cycle. Blackline Master #13, Experiment #2: Erosion, allows study of what determines the rate and amount of erosion. Blackline Master #14, Experiment #3: Fast Evaporation, gives the opportunity to measure and determine rates of evaporation. The amount of water used is not critical as long as it is the same in both containers. Blackline Master #15, Experiment #4: Terrarium, ties the water cycle and biology together to demonstrate that they are both linked. Blackline Master #16, Experiment #5: Transpiration, will amaze students as they discover how much water plants give to the atmosphere. Blackline Master #17, Experiment #6: Frost, teaches that frost is not frozen water; it is vapor that turns directly to ice crystals. Blackline Master #18, Experiment #7: Salty Water to Fresh Water, shows principles of evaporation and condensation while teaching kids how to distill or desalinate saltwater. 8

13 Blackline Master #19, Experiment #8: Holding Heat, provides insight into why large lakes and oceans are so important in controlling temperatures around the world. Blackline Master #20, Additional Internet Sites, goes further than the sites listed in Fact Sheet Quiz. It provides a large number of links, downloadable projects, lesson plans, and fun activities for students. Preview all Internet sites before recommending them to students to be certain they are appropriate for your intended use. ANSWER KEY Blackline #1, Pre-Test 1. The water cycle is the cycling of water from gas to liquid or solid, as it goes from condensation to precipitation to runoff to evaporation. It spreads water around the Earth. 2. The sun is the source of energy for the water cycle. 3. Precipitation is any form of water that falls from clouds. It may be rain, snow, sleet, or hail. 4. Condensation is when invisible water vapor becomes visible as water droplets or ice crystals. This is commonly seen as clouds, or it could be dew or frost. 5. Evaporation is when liquid water disappears into invisible gas in the air. 6. Transpiration is when trees, bushes, and plants give off water through their leaves. 7. Percolation is when water sinks, seeps, or soaks into the ground. 8. Runoff is when water or melted snow flows downhill, eventually to rivers or bodies of water. 9. Water can be in three phases, even at the same time. 10. A rain gauge measures rainfall. Blackline Master #2, Post-Test 1. Liquid, solid, or gas. These can be also referred to as water, ice, or vapor. Note that vapor may also refer to visible clouds but in this program, it signifies invisible water as a gas. 9

14 2. Precipitation may be rain, snow, sleet, or hail. 3. Plants remove water from the ground through capillarity and then release it into the air as water vapor through transpiration. 4. No, the water cycle never stops. 5. Frost and dew are found outside after a clear night with calm wind, when the relative humidity reaches 100%. 6. Evaporation is when liquid water disappears into invisible gas in the air. 7. Transpiration is when trees, bushes, and plants give off water through their leaves. 8. Condensation forms clouds, water droplets, dew, or frost. These are visible forms of water. 9. Percolation is when water sinks, seeps, or soaks into the ground. 10. Clouds can block and reflect sunlight when they are thick to keep us cool. At night, thick clouds act like a blanket to help the Earth retain heat. Blackline Master #3, Discussion Questions 1. The water cycle continues because heat from the sun lingers in the air and in the water, even after sunset. Each portion of the cycle requires another portion to happen. 2. The more direct sunlight an area gets the warmer its climate will be. Increased temperature means a more active water cycle due to increased evaporation. Areas with a lot of sun and bodies of water will have warm and humid (rainy) climates. Areas with less sun (nearer to the poles) will be colder. The water cycle will continue but on a slower pace. These areas will have cold climates that are drier unless they are near large bodies of water. 3. Transpiration assists in evaporation. It removes a large amount of water from the ground wherever there are forests, farm fields, grass, or other plants or bushes. 4. Evaporation generally leaves pollutants and contaminants behind. Fresh water falls in rain and snow. Snow melts and along with rain, it flows into lakes or percolates into the ground to restore aquifers. 5. If the water cycle stopped, eventually life would end as we 10

15 know it because people, plants, and animals would run out of sources of fresh water. 6. Snow, sleet, or hail. 7. We see condensation as dew or frost on grass and windows. We also see condensation as water droplets on the outside of a cold soda bottle. 8. Clouds can block sunlight to give a region a cool climate. If the clouds carry a lot of moisture, they can produce daily precipitation to give a region a wet climate. 9. Plants help in evaporating water that falls on their leaves, and water that transpires from their leaves. Plant roots help to reduce runoff by slowing how fast water moves on the ground. 10. Precipitation soaks into the ground and it causes runoff. Runoff fills rivers or bodies of water. The more water that is spread out on the ground, the more evaporation occurs. Transpiration pulls water out of the ground and contributes to evaporation. As evaporation increases, the air becomes saturated and we get condensation. Condensation produces clouds which grow to the point of producing precipitation. Blackline Master #4, Video Quiz 1. False. The water cycle never stops. 2. True. 3. True. 4. True. 5. False. The water cycle is everywhere. 6. True. 7. True. 8. False. There is water in the air and in the ground in a desert. 9. True. 10. True. Blackline Master #6, Word Search #1 11

16 Blackline Master #7, Word Search #2 Blackline Master #8, Crossword Puzzle #1 Across Down 3. porous 1. ecosystem 6. sediment 2. cycle 7. meteorologist 3. particles 11. hail 4. sun 12. frost 5. climate 8. reflect 9. solid 10. vapor Blackline Master #9, Crossword Puzzle #2 Across Down 4. clouds 1. moisture 6. runoff 2. temperature 7. erosion 3. percolate 8. humid 5. dew 10. precipitation 9. weather 11. glacier 12. sleet 13. weather 12

17 Blackline Master #10, Crossword Puzzle #3 Across Down 3. dissolve 1. evaporation 5. rain 2. condensation 8. snow 4. sublimation 9. transpiration 6. liquid 11. phase 7. groundwater 12. ocean 10. sea Blackline Master #11, Fact Sheet Quiz 1. c 2. d 3. b 4. e 5. a Blackline Master #12, Experiment #1: Make the Water Cycle 1. Heat makes the water boil. 2. The water evaporates faster as it boils. 3. Water droplets (condensation) appear on the bottom of the pot, and then fall as precipitation. 4. This is the same process that occurs in the water cycle. 5. The ice was used to cool the air faster and resulted in increased condensation. Blackline Master #13, Experiment #2: Erosion 1. The water slowly soaks into the sand when sprayed gently. 2. When sprayed close up, the force of the water erodes the pile and moves the sand grains. 3. The sand and water run off and go down the slope. 4. Erosion depends on how hard the rain falls and on how loose the soil is that the rain lands on. 5. More water can go into the sand if it is sprayed gently, or if grass or some other plant is grown to hold the sand together and protect it from the direct force of falling water. You can also put the sand in a container or build a fence or wall around it. Blackline Master #14, Experiment #3: Fast Evaporation 1. Answers will vary. 2. Answers will vary but times should be longer than when the water is fanned. 13

18 3. The fan helps the water evaporate by constantly exposing more of the water (molecules) to air. 4. The closer the fan is to the water, the faster evaporation is. The faster the air moves from the fan, the faster evaporation is. 5. Wind increases the rate of evaporation. Blackline Master #15, Experiment #4: Terrarium 1. Condensation occurs on the inside of the glass. 2. The water evaporates, condenses on the glass, and then drips into the soil. 3. The plants should live and grow. 4. This is a closed community where the water is cycled from liquid to gas to vapor, and shared in the community. 5. We see evaporation from the cap, transpiration from the plant, condensation on the jar, and precipitation as water droplets fall, or run down, the sides of the jar. Blackline Master #16, Experiment #5: Transpiration 1. We find water in the bags. 2. The water comes from the leaves of the plant. It traveled up from the ground in the plant's roots. 3. Leafy plants and trees should transpire more than those with needles. 4. Over time, it is possible to get enough water to drink, especially if you use multiple bags. Blackline Master #17, Experiment #6: Frost 1. Tiny crystals of ice are in the bag. 2. The ice crystals came from the vapor that was in your breath. 3. This is the process of condensation. 4. After a half hour, we see water droplets from the melted ice. 5. There is moisture in our breath and in our bodies. Blackline Master #18. Experiment #7: Salty Water to Fresh Water 1. Water condenses to form droplets in the tube. 2. The empty bottle receives water from droplets falling from the tube. 14

19 3. Dark colors absorb more heat. Warmer water evaporates faster, so it speeds up the process. 4. The water in the clear bottle should not be salty. 5. Desalination or distillation. Blackline Master #19, Experiment #8: Holding Heat 1. The thermometer in the empty cup cools fastest. 2. Heat from outside the refrigerator will change the readings on the thermometers. 3. Yes, both thermometers should end up at the same temperature. 4. The thermometer in the empty cup warms fastest. 5. Water is dense and it has a high capacity to retain heat. 6. Cities near large bodies of water are more likely to have a climate where the temperatures don't change very fast or very much, compared to cities not near large bodies of water. EXTENDED LEARNING ACTIVITIES Tour a golf course with a groundskeeper to hear how he or she maintains the greens and how things such as rainfall, sunlight, dew, type of grass, angle of slopes, fertilizers, and pesticides are all a big factor. A field trip to a nearby National Weather Service office will introduce the students to people who focus on water's role in weather and climate. Aside from forecasters, many offices employ a hydrologist. Visit the local water utility to see how they secure fresh water and provide it to your community. Invite a local TV weather forecaster to talk about the water cycle and some of the extremes it produces in your area. Ask a person from a city or county parks department to lead a field trip through a park where the students can observe the role of the water cycle in plants, and in erosion. 15

20 SCRIPT OF NARRATION Water is as old as the Earth. As far as we know, the amount of water on Earth has never changed. That's amazing when you think that the water in your faucet may have been deep in the sea millions of years ago. Or it may have been in a glacier for a thousand years. When you are done with it, it goes down the drain, and sooner or later, back to a lake or ocean where it may rise up into the sky and form a cloud that travels around the world to be used again. All over the planet, the sun helps nature recycle water in the water cycle. The water cycle has three main parts. Evaporation is when water turns into invisible water vapor and rises into the air. Condensation is when water vapor forms clouds, dew, or frost. And precipitation is when water falls from clouds as rain, snow, sleet, or hail. There's also a fourth part to the water cycle. It's called runoff; and that's when water runs downhill to flow into streams, lakes, or oceans. In the water cycle, we see water's different forms and properties. It can be solid ice that does not change shape, liquid water that moves and flows, or water vapor that floats in the air. The parts of the water cycle can control the climate of cities worldwide. Some places stay warm and wet, while others stay cold and dry. The water cycle is like an engine and the fuel for it is heat from the sun. The more heat that comes from the sun, the faster the water cycle works. At night, and even in places where you don't have much heat, the water cycle continues as liquid water, changes to ice, or water vapor, and back again. We call these phase changes. The water cycle makes sure that clean water falls from the sky and is spread around the Earth in one way or another. This makes it possible for people, plants, insects, and animals to survive and live almost anywhere. Evaporation is when tiny water droplets rise into the air as clean water vapor. Heat from the sun makes evaporation go faster. That's why, if you heat a pot of water for a long time, it turns to 16

21 steam and the water disappears. Moving air or wind also speeds up evaporation. Water vapor is invisible, but when there is a lot in the air, we feel the moisture on our skin. In the summer, people say the air is humid when it is filled with water vapor. After the rain ends on a warm day, we watch how quickly puddles and pavement dry off as the water evaporates. From salty oceans, lakes, and even swimming pools, water evaporates as fresh water. It is not always easy to notice when water is deep, but if you watch closely and take measurements, you'll find that all water evaporates into the air. Water that is in the ground can also evaporate, but that is slower since soil particles get in the way. Trees and plants help water turn into water vapor through transpiration. Transpiration is when the leaves of plants give off water that evaporates into the air. In a forest, transpiration plays a big part in the water cycle. The roots of plants, bushes, and trees pull water out of the ground, and then the leaves allow it to escape. You can do a simple experiment to prove this. Just put a clear bag over some leaves of a tree or bush, for an hour. Examine it and you'll find clean water. Did you know that ice can turn directly into water vapor without melting first?! When ice turns straight to water vapor, that's called sublimation. Sublimation is how snow can disappear after a few days, even when the temperature stays below freezing. It doesn't melt. It changes directly to vapor. You can see this by leaving ice cubes in your freezer for a few weeks. Notice that they gradually get smaller and smaller as the ice changes phase from solid to vapor. Condensation is when water vapor changes to a bunch of tiny water droplets that we see together as clouds. Sometimes these clouds are made of crystals of ice instead of water droplets. Condensation happens when air cannot hold any more water vapor. To make condensation, just keep filling the air with water vapor by evaporating more and more of it. When we shower, many of us make condensation clouds. 17

22 The clouds that nature creates take on many shapes, sizes, and colors. They form at any height and sometimes they even form on the ground as fog. These clouds make it easy for wind to push a lot of water around the Earth to places that need moisture. Clouds can keep us cool by blocking sunlight during the day. Another way to make condensation is to cool the air. This can happen when wind blows over cool water or cool land, or when air rises up the side of a mountain. There are two special kinds of condensation where no cloud is formed. They both happen after a clear night, with calm wind. Sometimes we wake up to find small beads of water on grass, or cars. That's dew. When the temperature is below freezing you might see ice crystals instead, especially on windows. That's frost. You can tell that it didn't fall from the sky because the sky is clear. Dew and frost happen when the temperature cools down and the air can't hold any more water vapor. In deserts, these are important ways for plants, insects, and animals to get water. You've probably noticed that after you take something out of the refrigerator, you see water droplets form on it. We also notice condensation on a glass of ice water. When you take something out of the freezer, you find ice crystals on that. As clouds get thicker, the water droplets inside of them grow heavy enough to fall. Water or ice that falls from clouds is called precipitation. Precipitation is rain, snow, sleet, or hail. Rain can cool off a hot city, help to fill a reservoir, and supply water to ecosystems. Too much rain causes problems. Lakes levels can rise and flood people's homes. Flood water can drown animals, people, and even plants and trees. The places on Earth that get the most rain are near large bodies of water, near the equator. Away from the equator, snow falls in layers to keep the ground from getting too cold. Too much snow at once can stop us from getting where we want to go. Snow that piles up is very heavy, and it may damage tree branches and property. Sleet is half frozen rain or half melted snow that can make a 18

23 slushy mess. Hail is pieces of ice that fall from powerful thunderstorms. When hail is large, it damages plants, crops, trees, and rooftops. All precipitation delivers water to the Earth's surface. A scientist who predicts precipitation is called a meteorologist. Runoff describes what happens to precipitation after it hits the ground. It simply will run off, downhill. Of course if it is snow, sleet, or hail, it has to melt first, but a lot of the water that falls from the sky flows in streams and rivers until it ends up in a lake or ocean. When water runoff is always in the same path or when it is very heavy and fast, it carries pieces of soil and rock and moves them downhill. That's called erosion. You can see erosion by spraying water onto a pile of sand. Runoff from heavy precipitation can be destructive. It can fill streams with solid soil pieces, called sediment, that make it hard for fish to breath. Heavy runoff can also carry pollution great distances. It can muddy the water so plants have a hard time getting sunlight to remain healthy. Runoff may weaken tree roots. It's always worse in cities with a lot of pavement. Runoff is also heavy in fields where there is little grass or plant life to help slow the water and soak it up. It's a good idea for any construction area to use fences to keep soil and pollutants from being washed away. Precipitation that does not run off slowly soaks into the soil. This is called percolation. If the ground is sandy, water can percolate into it pretty fast. When the ground lets water soak in fast, we say it is porous. But if the ground has a lot of clay in it, then it's not very porous and the percolation will be slow. As the water sinks into the ground, the soil and plants help to filter it and clean it. You can demonstrate how porous something is using muddy water, cotton balls, and a funnel. Pour the water into the cotton in the funnel to see how fast it moves through and to see how much of the sediment the cotton can catch. Water that percolates down into the ground is then called groundwater. All forms of water take a lot of heat from the sun to slowly 19

24 warm up. Once water is warm, it takes a long time to cool down, so all parts of the water cycle control temperature, precipitation, and climate. Climate is the average kind of weather that a place has. Islands with a lot of sunshine near the equator have climates that are humid and rainy because the sun's heat speeds up evaporation, condensation, precipitation, and runoff. All parts of the water cycle are connected. In sandy deserts, dry climates include hot days and cold nights. Without much water from the water cycle, it's easier for the temperature to rise and fall fast. Water plays an important role on Earth in weather and climatic patterns. Runoff from precipitation can wear things down in erosion, and carry them away. Water can also dissolve anything that sits in it long enough, so we call it the universal solvent. This makes water valuable in keeping ecosystems healthy. The water cycle produces climates where humans and animals can live and find fresh water. Now that you are Water Smart, let's take a quiz. True or False: Number one. The water cycle stops at night. Number two. Hail is a type of precipitation. Number three. Percolation helps to clean water. Number four. Dew is condensation. Number five. There is no water cycle where it is cold. Number six. Evaporation is faster when it is warm. Number seven. Snow helps to deliver fresh water. Number eight. There is no water anywhere in a desert. Number nine. There is more runoff on pavement than on grass. Number ten. Plants help out in the water cycle. 20