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  An Ocean of Air

  Why the Wind Blows and Other Mysteries of the Atmosphere

  Gabrielle Walker

  Table of Contents

  Title Page

  Table of Contents

  ...

  Copyright

  Dedication

  Epigraph

  CONTENTS

  PROLOGUE

  PART 1

  CHAPTER 1

  CHAPTER 2

  CHAPTER 3

  CHAPTER 4

  PART 2

  CHAPTER 5

  CHAPTER 6

  CHAPTER 7

  EPILOGUE

  ACKNOWLEDGMENTS

  SUGGESTIONS FOR FURTHER READING

  ENDNOTES

  INDEX

  HARCOURT, INC. • Orlando Austin New York San Diego Toronto London

  Copyright © Gabrielle Walker, 2007

  All rights reserved. No part of this publication may be reproduced

  or transmitted in any form or by any means, electronic or mechanical,

  including photocopy, recording, or any information storage and retrieval

  system, without permission in writing from the publisher.

  Requests for permission to make copies of any part of the work should

  be submitted online at www.harcourt.com/contact or mailed to the

  following address: Permissions Department, Harcourt, Inc.,

  6277 Sea Harbor Drive, Orlando, Florida 32887-6777.

  www.HarcourtBooks.com

  First published in Great Britain by Bloomsbury in 2007

  Library of Congress Cataloging-in-Publication Data

  Walker, Gabrielle.

  An ocean of air: why the wind blows and other mysteries of the atmosphere/Gabrielle Walker.

  p. cm.

  Includes bibliographical references and index.

  1. Atmosphere—History. 2. Air—History. 3. Science—History. I. Title.

  QC855.W35 2007

  551.509—dc22 2006032359

  ISBN 978-0-15-101124-7

  Text set in Columbus MT

  Designed by April Ward

  Printed in the United States of America

  First U.S. edition

  A C E G I K J H F D B

  For Fred and Hubert

  I adorn all the earth.

  I am the breeze that nurtures all things green.

  I encourage blossoms to flourish with ripening fruits.

  I am led by the spirit to feed the purest streams.

  I am the rain coming from the dew

  That causes the grasses to laugh with the joy of life

  —Hildegard of Bingen,

  TWELFTH-CENTURY ABBESS

  CONTENTS

  Prologue [>]

  PART 1

  COMFORT BLANKET

  CHAPTER 1: THE OCEAN ABOVE US [>]

  CHAPTER 2: ELIXIR OF LIFE [>]

  CHAPTER 3: FOOD AND WARMTH [>]

  CHAPTER 4: BLOWING IN THE WIND [>]

  PART 2

  SHELTERING SKY

  CHAPTER 5: THE HOLE STORY [>]

  CHAPTER 6: MIRROR IN THE SKY [>]

  CHAPTER 7: THE FINAL FRONTIER [>]

  Epilogue [>]

  Acknowledgments [>]

  Suggestions for Further Reading [>]

  Endnotes [>]

  Index [>]

  PROLOGUE

  AUGUST 16, 1960 7 A.M.

  TWENTY MILES ABOVE NEW MEXICO, Joe Kittinger was hanging in the sky. For eleven minutes he remained there, poised in an open gondola that twirled slowly beneath a vast helium balloon. Though it was long past sunrise, the air around was dark as midnight. Far below, where Earth's surface curved away to the horizon, a glowing blue halo stood out against the blackness of space.

  This glow was the atmosphere, the single greatest gift our planet possesses. Earth's glorious blue color comes not from the oceans, but from the sky, and every astronaut who has seen that delicate halo has come back with the same tale: They couldn't believe how fragile it made Earth seem, and how beautiful.

  Back on the surface, robbed of that lofty perspective, we are inclined to take our atmosphere for granted. Yet air is one of the most miraculous substances in the universe. Single-handedly, that thin blue line has transformed our planet from a barren lump of rock into a world full of life. And it is the only shield that stands between vulnerable earthlings and the deadly environment of space.

  Kittinger, however, had journeyed beyond its protection. Up on the edge of space, the air was so tenuous that if his pressure suit failed he would die within minutes. First his saliva would bubble, then his eyes pop and his stomach swell, and finally his blood would boil. Despite all the risks he had taken as a test pilot for the U.S. Air Force, he had never been in greater danger.

  Alone in his gondola, he was acutely aware of the menace. The near-vacuum seemed strangely substantial, like an enveloping layer of poison. The darkness rattled him, as did the curtain of clouds far below that were cutting off all views of home. He radioed to ground control. "There is a hostile sky above me," he said. "Man will never conquer space. He may live in it, but he will never conquer it."

  He shuffled toward the door, weighed down with 150 pounds of survival gear, instruments, and cameras, and stood for a moment, his boots protruding slightly over the ledge. Several inches below his feet, a sign declared "highest step in the world." He took a single breath of pure oxygen from within his tightly sealed helmet. "Lord, take care of me now," he said. And then he jumped.

  At first, Kittinger had no sense of falling. He could see the white swirls of storm clouds far below his feet, but they were growing no closer. The air around him was so thin that there was no sound or wind or any other clue that he was plunging through the most hostile environment a human being had ever faced. Spread-eagled in the sky, he felt almost serene. He could have been floating on a sea of nothingness.

  Dangerous though the environment was, it was still protecting him. Lack of pressure isn't the only hazard in space; there is also a constant barrage of radiation, much of it from our own sun. Every day, along with the warmth and light that allow us to live on Earth, the sun sends out x-rays and ultraviolet light from the deadly end of its rainbow.

  Thanks to our intervening sky, this radiation never reaches the ground. Fifty miles above Kittinger's head, a few scarce atoms of air were acting as sentinels, intercepting and absorbing those lethal x-rays. In the process, these atoms were being ripped to shreds and heated to temperatures of 2 ,000 degrees. They form the ionosphere, a tenuous region of the atmosphere where electricity is king. Unseen from Earth's surface, giant blue jets of fire leap up to this layer from the tops of thunderclouds, in bolts of reverse lightning. Here, meteorites from space are obliterated in the glorious blaze of light that we call shooting stars. They splatter the air with floating layers of metal that allow electric currents to swoop around the upper Earth. Radio broadcasts reflect from this charged surface as they bounce their way around the globe.

  Farther up still, the air above Kittinger was facing an even more violent attack—from a force known as the solar wind. Electrically charged jets of particles from the sun were barreling toward Earth at more than a million miles an hour, ready to strip away our atmosphere and send it streaming out behind the planet like the tail from a giant comet.

  But to do so, it would first need to pass one of our staunchest defenders—Earth's magnetic field. On the surface we scarcely notice this field, except when it helpfully tugs compass needles into pointing north. But its arching influence extends tens of thousands of miles above us, and it forces the solar wind to part around it like water around a ship's bow. Far above Kittinger's head, those protective magnetic arcs were channeling the solar wind harmlessly away. The field is all but
impenetrable, allowing just a few particles to leak into the polar regions, where they collide with the atmosphere to provide the dancing glows of the northern and southern lights.

  Still, almost all our protective atmosphere lies within a few miles of the surface, and when Kittinger took that high-altitude leap of faith, most of it was beneath him. A few seconds into his fall, he kicked and twisted until he was facing upward. Now he could see the taut white sphere of his balloon shooting up into the darkness at a breakneck speed. This, Kittinger knew, was an illusion. The balloon was still floating gently where he had left it. He was the one falling down through the sky at close to the speed of sound.

  Kittinger was tumbling now through another of our world's vital protective shields—the ozone layer. All around him, any invisible ultraviolet rays that had slipped through the ionosphere were being soaked up by a diffuse cloud of invisible gas. Ozone is miraculous stuff. Near the ground it is sometimes created by lightning bolts or spark plugs. It smells like burning electrical wires and makes you choke. But high aloft it is both vigilant and resilient. Split asunder by ultraviolet rays, the ozone molecules around Kittinger were calmly re-forming. Like the burning bush encountered by Moses, they are constantly ablaze but never consumed.

  Seventy thousand feet. Sixty thousand. Kittinger was now below the point where even a pinhole in his suit would have allowed his blood to boil off into space. But he had one last hazard to face: He had reached the coldest part of his descent, where the temperature had fallen to 98 degrees below zero and the heating elements in his suit mattered most.

  Then there were clouds, and wind, and all the signs that Kittinger was finally approaching home. Forty thousand feet. Thirty thousand. He was about to drop past the altitude of Mount Everest. Any jet plane that happened to be flying nearby would see a man in a strange suit shooting past the window. The clouds he had seen from the gondola, blocking his view of home, were now rushing toward him. Though he knew they were only insubstantial water droplets, he still braced himself unconsciously for an impact, pulling his legs upward in anticipation. The moment he hit the clouds, his parachute opened and he knew he would live. "Four minutes and thirty-seven seconds free fall!" he said into his voice recorder. "Ahhhhh boy!"

  Kittinger had now fallen safely into the lowest part of the atmosphere—the troposphere. The air here isn't so much a protector as a transformer, a thick, life-giving blanket of air, wind, and weather that turns our planet into home. After the bone dryness of space, flecks of moisture from the clouds fogged Kittinger's face plate. He could feel the tug of the thickening air. The sky was now full of life, though he couldn't see it. Bacteria that had launched themselves into the wind were hitching a ride on cloud droplets, seeking out new victims farther afield. Insects were wafting their way to new feeding grounds and seeds to more fertile soil.

  And, praise be, two rescue helicopters were hovering nearby. With the ground fast approaching, Kittinger struggled to cut away his heavy instrument kit for the sake of a softer landing, but one last hose resisted his knife. He gave up and instead raised the shield on his helmet and took a deep breath of fresh air. As the air flushed into his lungs, oxygen leapt across thin membranes into the cells of his blood and turned them a glorious, life-giving red. (And some of it set off on a well-worn rampage that had been going on since Kittinger took his first breath of air. These rogue molecules would continue to line Kittinger's face and wear down his body, in the process we know as aging.)

  Finally, after a flight time of thirteen minutes and forty five seconds, Joe Kittinger crashed unceremoniously into the scrub, twenty-seven miles west of Tularosa, New Mexico. Medical personnel, ground crew, supporters, and journalists poured out of the helicopters and rushed over to where he lay. He smiled at them through his open face plate. "I'm very glad to be back with you all," he said. Though the desert landscape was far from lush, to a man who had seen beyond the atmosphere, the yuccas and sagebrush seemed full of life. "Fifteen minutes before I'd been on the edge of space," he said later. "And now, to me, I was in the Garden of Eden."

  Captain Joseph W. Kittinger Jr. of the U.S. Air Force is the man who fell to Earth and lived. Nobody has ever managed to emulate his feat. His passage home from the edge of space, from thin air to thick, illustrates something extraordinary about our planet. Space is almost close enough to touch. Only twenty miles above our heads is an appalling, hostile environment that would freeze us, and burn us and boil us away. And yet our enfolding layers of air protect us so completely that we don't even realize the dangers. This is the message from Kittinger's flight, and from every one of the pioneers who have sought to understand our atmosphere: We don't just live in the air. We live because of it.

  PART 1

  COMFORT BLANKET

  CHAPTER 1

  THE OCEAN ABOVE US

  NEARLY FOUR HUNDRED YEARS AGO, in a patchwork of individual fiefdoms that we now call Italy, a revolution of ideas was struggling to take place. The traditional way to understand the workings of the world—through a combination of divine revelation and abstract reasoning—had begun to come under attack from a new breed. These people called themselves "natural philosophers," because the word "scientist" had not yet been invented. To find out the way the world worked, they didn't sit around and talk about it. They went out and looked. This was not an approach that was likely to find favor with the Church, home of received wisdom, or with its instruments—the whispering Inquisitors, with their hotline back to Rome. Now, a certain natural philosopher had fallen very foul of those Inquisitors and been forced to stop his investigations into the structure of the heavens. His name was Galileo Galilei, and our story begins with him.

  Convent of Minerva, Rome

  JUNE 22, 1633

  I, Galileo Galilei, son of the late Vincenzo Galilei, Florentine, aged seventy years, arraigned personally before this tribunal, and kneeling before you, most Eminent and Reverend Lord Cardinals, Inquisitors general against heretical depravity throughout the whole Christian Republic ... have been pronounced by the Holy Office to be vehemently suspected of heresy, that is to say, of having held and believed that the sun is the center of the world and immovable, and that the earth is not the center and moves:

  THEREFORE, DESRING TO REMOVE FROM THE MINDS OF YOUR EMINENCES, AND OF ALL FAITHFUL CHRISTIANS, THIS STRONG SUSPICION, REASONABLY CONCEIVED AGAINST me, with sincere heart and unfeigned faith I abjure, curse, and detest the aforesaid errors and heresies ... and I swear that in the future I will never again say or assert, verbally or in writing, anything that might furnish occasion for a similar suspicion regarding me.

  As the great Galileo rose from his knees at the end of this infamous, and forced, recantation, he is said to have muttered "Eppur si muove!" ("And yet it moves!"). He knew in his heart that Earth moves around the sun, in spite of what the Inquisitors had made him say. Still, devoutly religious as he was, he had no taste for defying his own church. Nor had he any desire to share the fate of the unfortunate monk Giordano Bruno, who a few decades earlier had been publicly burned for holding similar views. Galileo may have been the most famous philosopher in all Italy, but he knew that in itself wouldn't save him from the fire.

  And though he was now seventy years old, frail, and steadily losing his sight, he was not yet ready to die. He had damaged his eyes by staring through a telescope at wonders he himself had discovered: blemishes that appeared periodically on the surface of the sun; craters on the moon; distant but distinct moons circling the planet Jupiter (who would have thought that other planets could have moons of their own?), and stars that nobody knew existed. Now, before the cataracts and glaucoma finally clouded his sight, in secret, if necessary, he had one last task to complete. Galileo had seen this "trial" coming; he'd known for some time that he couldn't continue his study of the heavens. So for some years he had been discreetly changing tack, turning his attention inwards to Earth itself. And, failing eyesight notwithstanding, he was about to change the way we see the most apparently ordinary
substance in the world: air.

  The Inquisitors knew nothing of this. They were satisfied with his recantation, and decided, graciously, to spare his life. He would be allowed to return to his villa at Arcetri in Florence, though he should understand that he was still considered dangerous and would therefore be held under house arrest. There would be no visitors, save those given prior permission by the Church. Meanwhile, Galileo himself was to spend his time reciting the holy psalms as penance, and praying for his immortal soul.

  Galileo returned to his villa as instructed and performed his penance diligently. But the Inquisitors had also obliged him to swear never again to publish work that might offend the Holy Office, and he had no intention of complying. For with him to Arcetri he had taken a certain manuscript that was already nearly finished.

  He had started the experiments it described while awaiting his summons to Rome. Having turned away from his telescope, Galileo had become fascinated instead by the different ways that objects move through the air. The result was to become his masterpiece. The manuscript already recounted findings that would become just as famous as the moons of Jupiter. For instance, Galileo had made the surprising discovery that Earth's gravity doesn't care in the least how much something weighs. Drop a cannonball and a pebble from a high tower, and both will reach the ground at exactly the same moment.

  But within its pages was another discovery that would prove to be less famous yet no less significant. Galileo had measured the weight of air.

  This might seem like a bizarre notion. How can something so insubstantial as the air weigh anything at all? In fact our planet's air is constantly pushing down on us with great force. We don't notice this because we're used to it, like lobsters sauntering along on the seafloor, unaware of the crushing weight of the ocean of water above them. We give our own overlying air-ocean so little respect that we even describe anything that's full of air as being "empty."