E C Pielou

the university of chicago press • chicago and london

E.C. PIEL OU, former professor of mathematical ecology and Killam Professor at Dalhousie University, has been a naturalist all her life. She is the author of many books, most recently Fresh Water, A Naturalist's Guide to the Arctic, and After the Ice Age, all published by the University of Chicago Press.

The University of Chicago Press, Chicago 60637 The University of Chicago Press, Ltd., London © 2001 by The University of Chicago All rights reserved. Published 2001 Printed in the United States of America

10 09 08 07 06 05 04 03 02 01 12 3 4 5 ISBN: 0-226-66806-1 (cloth)

Library of Congress Cataloging-in-Publication Data Pielou, E.C.

p. cm. Includes index

ISBN 0-226-66806-1 (alk. paper)

1. Force and energy. I. Title QC73.P54 2001

530—dc21 00-048841

@ The paper used in this publication meets the minimum requirements of the American National Standard for Information Sciences—Permanence of Paper for Printed Library Materials,ANSI Z39.48-1992.

In memory of Patrick

CONTENTS

Preface ix

Some Notes on Scientific Notation xi

1 Energy Is Everywhere 1

2 What Is Energy? Some Preliminary Physics 5

3 Energy and Its Ultimate Fate 13

4 Solar Energy and the Upper Atmosphere 21

5 Energy in the Lower Atmosphere: The Weather Near the Ground 36

6 The Sun, the Wind, and the Sea 47

7 The Energy of Ocean Waves 65

8 The Energy of the Tides 83

9 How Surface Energy Shapes the Land 92

10 Chemical Energy 108

11 Energy Enters the Biosphere 116

12 Further Travels of Energy in the Biosphere 131

13 The Warmth of the Earth: Nuclear Reactions Sustain All Life 139

14 The Earth's Internal Energy 149

15 How the Earth Sheds Its Warmth 157

16 Electromagnetic Energy 171

17 Wave Energy: Sound Waves and Seismic Waves 187

18 Wave Energy: Electomagnetic Waves 197

19 How Energy Is Used 210

Epilogue 223 Notes 225 Index 241

PREFACE

When Robert Louis Stevenson wrote in a lighthearted vein, "Life is so full of a number of things / I'm sure we should all be as happy as kings," he mentioned only things and not events. This book is about events in the natural world—all kinds of events. They are as numerous and as interesting as things, and much more thought provoking. The salient point about events is that without energy they couldn't happen. Without energy, nothing would ever happen. Energy is as indispensable an ingredient of the universe as matter is. It is extraordinary that mentioning the word "energy" makes most people envision only power stations, hydroelectric dams, the price of oil, or athletes.

I consider energy from the point of view of a naturalist. To me "natural history" consists of more than the study of mammals, birds, butterflies, trees, and flowers plus thousands of other living organisms. The subject also includes the study of weather, of rivers and lakes, the oceans, the structure of the land, and much more: everything in which movement is visible or in which you know movement is happening although you can't see it. The movement may be too slow, as in tree growth and mountain building, or concealed, as in molten rock flowing deep underground, or invisible, as electric charges building up on clouds and on the earth's surface below.

The book contains no math apart from the occasional arithmetic calculation. The units in which speed, density, power, and the like are measured are written in scientific notation, as explained on page ix. It takes only a moment to grasp the principles, and any other style would be intolerably long-winded. The level of the book is about the same as that of articles in Scientific American or New Scientist.

As always, I am indebted to my husband, Patrick, and my editor at the University of Chicago Press, Susan Abrams, for contributing brainwaves and encouragement.

SOME NOTES ON SCIENTIFIC NOTATION

Powers of ten and of one-tenth

Likewise 0.1 = 1/10 = 10-1, 0.01 = 1/100 = 1/102 = 10-2,0.001 = 1/1,000 = 1/103 = 10-3, and so on.

Measurements

Area: One square meter (m) is written as 1 m2. Volume: One cubic meter is 1 m3.

Speed: One meter per second (s) is best written 1 m s-1 (not 1 m/s). Acceleration: One meter per second per second is best written 1 m s-2 (not 1 m/s2).

Density: One kilogram (kg) per cubic meter is best written 1 kg m-3 (not 1 kg/m3).

And so on, for any unit that would be spoken aloud as (something) per (something).

An exception to the rule: One kilometer per hour is 1 km/h because neither the kilometer nor the hour belongs to the international system of units (ISU).

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