Write to explain how a raindrop travels through the water cycle?. Extended Vocabulary atmosphere classify molecule natural disaster perspiration saturation transpiration Vocabulary conde
Trang 1Scott Foresman Science 3.5
Nonfi ction Cause and Effect • Captions
• Text Boxes
• Diagram
• Glossary
Water
ISBN 0-328-13822-3
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Scott Foresman Science 3.5
Nonfi ction Cause and Effect • Captions
• Text Boxes
• Diagram
• Glossary
Water
ISBN 0-328-13822-3
ì<(sk$m)=bdicch< +^-Ä-U-Ä-U
Trang 21 How are raindrops formed?
2 Why is rain important?
3 How big are raindrops?
raindrop is part of the water cycle
Write to explain how a raindrop travels through the water cycle
Include details from the book to support your answer
vapor condenses and turns to liquid high up in the atmosphere, what is the effect?
What did you learn?
Extended Vocabulary
atmosphere classify
molecule natural disaster perspiration saturation transpiration
Vocabulary
condensation
evaporation
groundwater
precipitation
water cycle
water vapor
wetlands
Picture Credits
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.
Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd).
Opener: Bruce Peebles/Corbis; 5 Bruce Peebles/Corbis; 6 (B) Color Box/ImageState; 10 (BR) Jose Luis Pelaez, Inc./Corbis;
11 Marc Muench/Getty Images; 12 (B) ©J B Pickering/Eye Ubiquitous; 13 Harolod Palo Jr./NHPA Limited.
Scott Foresman/Dorling Kindersley would also like to thank: 7 NASA/DK Images.
Unless otherwise acknowledged, all photographs are the copyright © of Dorling Kindersley, a division of Pearson
ISBN: 0-328-13822-3
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 permission(s), 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
by L.L Owens
Trang 3Water is everywhere, and it is constantly
changing form Rain, snow, sleet, and hail are all
forms of water They are also called precipitation
Evaporation is what happens when heat turns
water into water vapor Water vapor is an
invisible gas found in the air Depending on
conditions, it can either remain invisible or be
changed into visible water Condensation is what
happens when water vapor turns back into a
liquid
Most of the fresh water on Earth is frozen
as ice When rivers and lakes overfl ow, or when
the ground can’t take in any more water, wetlands
form You can also fi nd groundwater, or fresh
water, trapped below Earth’s surface between
underground rocks
The water cycle keeps water moving Water
travels from Earth’s surface into the air and back
again That’s how we get the steady supply of
fresh water we need to survive
What You Already Know
2
Water can be confusing to keep track of After all, it takes many forms and is constantly changing But without water, life could not exist It is
important that we know what’s going on with Earth’s water This book will help you understand how water gets around our planet
3
Trang 4The Water of Life
Rain is a type of precipitation It falls from
the clouds to Earth’s surface in the form of
liquid droplets Raindrops form when water
vapor condenses around small particles of dust
When raindrops get too heavy for a cloud to
hold them, they fall to the ground Then we
get wet!
Rain, if it falls too fast over too short a
period of time, can cause many problems for
humans and other living things Heavy rain can
make it diffi cult or unsafe to
travel It can even cause
natural disasters such
as mudslides and
fl ooding.Yet most of
the time, it is a lack of
rain that causes the most
harm to life on Earth
4
All living things need water to survive Rain is one way that many living things, such as plants and trees, get the water they need to live
Rainwater helps supply the water that our bodies’ systems run on We drink it, water our crops with it, and cook with it We also use it to wash our clothes, manufacture goods, and make electricity For all of those reasons, the water that comes from rainfall is critical to maintaining life
Rain like this can cause heavy fl ooding, mudslides, and other serious problems.
5
Trang 5Evaporation is an important
part of the water cycle During
the process of evaporation, water
changes from a liquid state into
a gas
Here’s how evaporation works
The Sun heats up water in rivers, lakes, and oceans
Once heated, the water turns into water vapor and
rises into the atmosphere All exposed areas of
water, including swimming pools and reservoirs,
are heated by the Sun and evaporate
On warm, sunny days large amounts of
water evaporate into the atmosphere.
water evaporates
6
Have you ever noticed steam rising from a cup
of hot cocoa or a bowl of chicken soup? If you have, then you’ve seen evaporation with your own eyes Steam is what water can look like before it turns to vapor and travels through the air
A process called transpiration is another way water moves back into the air Transpiration
is what happens when plants release water into the air through their leaves It’s similar to the process of perspiration, when water leaves the human body as sweat and evaporates into the air
Temperature plays a big role in evaporation
The hotter the water, whether it is found in a body of water or a living thing, the faster it will evaporate
Watery Planet
About 75 percent of Earth’s surface is covered with water Look at this view of Earth Everything that is blue or white is some form of water! Earth
7
Trang 6When water vapor cools in the
air, it turns into tiny water droplets
The water has changed its form, or
state, from a gas back into a liquid
This is a physical change called
condensation
A cloud is one visible result of condensation
Clouds form when water vapor condenses and
turns to liquid high up in the atmosphere When
you look at a cloud, what you are really seeing is
a large group of water droplets and ice crystals
clouds form
8
Now, think about the last time you had a glass
of lemonade on a hot day
You might have noticed water droplets form on the outside of your glass If you saw that happen, then you witnessed another example of condensation
The water droplets that form on cold glasses of liquid come from the warm air They begin as water vapor, which starts to cool down when it fi rst touches the glass Once it cools down enough, it changes state, or condenses, from
a gas to a liquid
Cloud Types
The three main types of clouds are cirrus, cumulus, and stratus Have you seen them before?
cirrus clouds
cumulus clouds
stratus clouds
9
Trang 7Remember the water droplets
that form clouds? When enough
of them condense into large
enough particles, they fall as rain
Clouds release the water droplets
that they contain when the droplets
become too heavy for the clouds to carry
Meteorologists usually classify water droplets
as rain when they reach a certain size The diameter
of a typical raindrop measures between one-half
millimeter and four millimeters Anything bigger
than four millimeters is likely to break up into
smaller drops
Snow
In the United States,
rain and snowfall are
measured in inches An
equal measure of snow
contains less water than
rain It can take fourteen
inches of snow to equal
the amount of water in
one inch of rain!
Snow falling in the city
Rain falls.
10
A rain shower contains raindrops of different sizes Individual raindrops change size and shape
as they fall Such changes mostly happen when individual raindrops bump into each other while they are falling Two raindrops might hit each other and form a bigger droplet Or they might hit and break up into many smaller drops
By using microscopes, scientists have been able
to describe the shape of water droplets Most raindrops start out in the shape of a sphere, but end up being shaped like a hamburger bun!
11
Trang 8Back to the Sea
Rain feeds Earth’s water systems
Those systems include rivers, lakes,
streams, and oceans Rivers, lakes,
and streams are all connected
through groundwater systems
and the water cycle Through
evaporation, precipitation, and the movement of
water, Earth’s water systems constantly interact
When a raindrop gets too heavy for a cloud
to hold, it falls to Earth That raindrop might fall
into a river It might land on top of a tree, splatter
onto a fl ower, or drop to the ground If you’re
outside, it might fall on you!
fl owing river
Water returns
to the sea.
12
Unless it lands in a body of water, a raindrop
is likely to either evaporate back into the air, or
be absorbed into the ground Sometimes, the ground reaches its saturation point and cannot absorb any more water
You can think of the ground as being like a sponge When a sponge has been fi lled with too much water, the extra water spills out When the ground reaches its saturation point, the extra water seeps out into streams, lakes, and wetlands
From the streams, lakes, and wetlands, water
fl ows to rivers Almost all rivers fl ow into the sea
Water that fl ows into the sea can evaporate immediately It can also sink below the surface and stay there for years
Underground Water
Some water travels deep underground
When it reaches a layer
of rock that it can no longer seep through, it can form underground lakes
underground lake
13
Trang 9The Complete
Water Cycle
A single raindrop is just a tiny part of the
water that moves through the water cycle
Earth’s water is limited But all of it moves
through the water cycle, which is always active
The water cycle never stops changing water
from one form to another or moving it from
one place to another
Heat from the Sun causes water to change
form as it travels When not in its liquid form,
water travels as water vapor, or water that has
evaporated Water also travels in clouds as water
droplets It can also move from place to place as
precipitation when it rains, snows, or hails
Water evaporates.
Water vapor condenses into tiny water droplets and forms clouds.
The Sun’s heat
warms water.
14
Everything on Earth is involved somehow
in the water cycle Plants and trees give off evaporated water that travels into the atmosphere When we sweat, the water produced enters into the water cycle too
Water reaches rivers, oceans, and lakes as precipitation and run-off Soil absorbs water, which can trickle down to the rocks beneath the soil Plants and trees can absorb some of that water to complete the cycle
Much of the water cycle is visible But other parts are invisible For example, in the summer, single trees might evaporate hundreds of gallons
of water a day!
Clouds move over land.
Rivers and streams fl ow back into the sea.
Water falls as precipitation.
Trang 10Glossary
that surrounds Earth
a category
natural disaster a natural event that happens
suddenly and causes severe damage
perspiration the process of perspiring,
or sweating
transpiration the process of green plants
giving off water through their leaves
1 How are raindrops formed?
2 Why is rain important?
3 How big are raindrops?
raindrop is part of the water cycle
Write to explain how a raindrop travels through the water cycle
Include details from the book to support your answer
vapor condenses and turns to liquid high up in the atmosphere, what is the effect?
What did you learn?
Extended Vocabulary
atmosphere classify
molecule natural disaster perspiration saturation transpiration
Vocabulary
condensation
evaporation
groundwater
precipitation
water cycle
water vapor
wetlands
Picture Credits
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.
Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd).
Opener: Bruce Peebles/Corbis; 5 Bruce Peebles/Corbis; 6 (B) Color Box/ImageState; 10 (BR) Jose Luis Pelaez, Inc./Corbis;
11 Marc Muench/Getty Images; 12 (B) ©J B Pickering/Eye Ubiquitous; 13 Harolod Palo Jr./NHPA Limited.
Scott Foresman/Dorling Kindersley would also like to thank: 7 NASA/DK Images.
Unless otherwise acknowledged, all photographs are the copyright © of Dorling Kindersley, a division of Pearson
ISBN: 0-328-13822-3
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 permission(s), 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