Ebook Water on earth

Earth Science Genre Nonfiction Comprehension Skill Sequence Text Features · Labels · Maps · Diagrams · Glossary Science Content Water on Earth Scott Foresman Science 5.7 ì<(sk$m)=bdjdeh< +^-Ä-U-Ä-U by Anna Padilla Vocabulary aquifer Water on Earth condensation by Anna Padilla evaporation precipitation reservoir salinity sleet sublimation water table Illustrations: 4, 6, 12, 14, 16, 18 Studio Liddell; 23 Bob Kayganich Photographs: Every effort has been made to secure permission and provide appropriate credit for photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R) Background (Bkgd) Opener: ©Raymond Gehman/NGS Image Collection; Title Page: ©Tom Stewart/Corbis; 2 ©David Pu’u/Corbis; 9 (T) ©Cosmo Condina/Getty Images, (B) ©Paul Linse/Corbis; 11 ©Tom Stewart/Corbis; 17 (TR) ©Graig Tuttle/Corbis, (CR) ©Gary W. Carter/Visuals Unlimited, 20 Dick Ruhl; 21 (TL) ©Patti Murray/Animals Animals/Earth Scenes, (TL) ©Stephen Ingram/Animals Animals/Earth Scenes, (CL) ©Eastcott/Momatiuk/Animals Animals/Earth Scenes, (BL) Brian Cosgrove/©DK Images, (BL) ©James A. Sugar/Corbis; 22 (BL) ©Jeff Daly/Visuals Unlimited; 23 (BL, BC) ©Henryk T. Kaiser/Index Stock Imagery, (BC) ©Frans Lemmens/Getty Images, (BR) ©Jim W. Grace/Photo Researchers, Inc. ISBN: 0-328-13934-3 Copyright © Pearson Education, Inc. All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to: Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025. 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05 How can the oceans The Pacific is the largest ocean. It is also the deepest. In its deepest spot, it is more than 11,000 meters deep. After the be described? Pacific, the largest oceans are the Atlantic, the Indian, and the Arctic. If you look at a globe, you will see that all of the world’s The Hydrosphere Most of Earth is covered with water. All of this water is very important to humans. It gives us a way to travel and a good source of food. More than half of the people in the United States live within 80 kilometers of an ocean. All of Earth’s waters together are called the hydrosphere. Ocean water makes up most of the hydrosphere. 2 oceans are connected. The oceans are all a little different from each other. Some oceans have more storms than others. They have different average temperatures and different amounts of salt. The levels of the ocean’s surfaces, or sea levels, are also a bit different. 3 Salinity What is the difference between lake water and ocean water? If you taste them both, you will notice that ocean water is very salty. Salinity is a measure of how salty water is. If you drink too much ocean water, it can make you sick. The oceans get their salt from rivers. Rivers dissolve tiny amounts of salt from rocks and soil. They carry this salt to the ocean. There, some of the water evaporates, leaving its salt behind. Ocean water is more salty in some places than others. In warm areas, ocean water has high salinity, because water there evaporates quickly. Places where rivers flow into oceans Temperature The temperature of ocean water is different in different places. Distance from the equator affects water temperature. Water near the equator is usually very warm. Water near the North and South Poles is usually very cold. Oceans’ currents also affect water temperature. They can carry warm water toward the poles. They can also carry cold water toward the equator. Look at the map below to see how these currents move. Ocean Resources have low salinity. Different salinities help make the ocean’s currents. Saltier water is heavier than less salty water, so it sinks. This sinking can cause currents. Most currents are caused by winds. Map Legend warm current cold current We get many products from the ocean. We get tuna and other fish to eat. We can also get salt from ocean water. This is done by letting the water flow into shallow ponds. The water evaporates. The salt is left behind. We can drink ocean water if the salt is taken out. This way of getting drinking water costs a lot of money. So it is not very common. This map shows currents on the surface of the water. Currents below the surface move in different ways. 4 5 Where is fresh water found? Groundwater Rain or melted snow that sinks into the ground is called Fresh Water Less than 100 of Earth’s water is fresh water. Humans need fresh water to drink. We also use it for cooking, cleaning, and watering crops. Almost all of Earth’s fresh water starts as rain or snow. Some of this water soaks into the ground. Some collects in rivers and lakes. Some is frozen in ice sheets and glaciers. Some places have plenty of fresh water. Other places do not have enough for the people who live there. No place has unlimited fresh water. People must be careful not to use too much. Water should be used wisely. 6 groundwater. As it sinks, this water fills spaces between small bits of soil and rock. It keeps sinking until it reaches something it cannot pass through, such as rock or clay. A layer of this material will cause groundwater to flow sideways instead of down. An aquifer is a layer of rock and soil that contains groundwater. Many people get their water from wells drilled into an aquifer. The top level of groundwater in an aquifer is the water table. The level of a water table changes. It rises when water is added by rain or melting snow. It falls when a long time passes without rain. The level will also fall when water is pumped out through wells faster than it is replaced. 7 ... - tailieumienphi.vn