An Ocean of Air: Why the Wind Blows and Other Mysteries of the Atmosphere

An Ocean of Air: Why the Wind Blows and Other Mysteries of the Atmosphere

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by Gabrielle Walker

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We don’t just live in the air; we live because of it. It’s the most miraculous substance on earth, responsible for our food, our weather, our water, and our ability to hear. In this exuberant book, gifted science writer Gabrielle Walker peels back the layers of our atmosphere with the stories of the people who uncovered its secrets:

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We don’t just live in the air; we live because of it. It’s the most miraculous substance on earth, responsible for our food, our weather, our water, and our ability to hear. In this exuberant book, gifted science writer Gabrielle Walker peels back the layers of our atmosphere with the stories of the people who uncovered its secrets:

• A flamboyant Renaissance Italian discovers how heavy our air really is: The air filling Carnegie Hall, for example, weighs seventy thousand pounds.

• A one-eyed barnstorming pilot finds a set of winds that constantly blow five miles above our heads.

• An impoverished American farmer figures out why hurricanes move in a circle by carving equations with his pitchfork on a barn door.

• A well-meaning inventor nearly destroys the ozone layer.

• A reclusive mathematical genius predicts, thirty years before he’s proved right, that the sky contains a layer of floating metal fed by the glowing tails of shooting stars.

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Editorial Reviews

William Grimes
…Ms. Walker, while cruising along at a breathtaking clip, manages to explain with exemplary clarity the chemistry of the atmosphere, the mechanics of wind and the role of the enveloping layers that swaddle the Earth, protecting it from the sun and occasionally putting on a grand show, like the northern lights…[she] takes her title from Evangelista Torricelli, an Italian mathematician and colleague of Galileo's who, marveling at the power and weight of the atmosphere, exclaimed in a letter in 1644, "We live submerged at the bottom of an ocean of air." This sense of wonder, transmitted down through the ages through generations of scientists, animates Ms. Walker's high-spirited narrative and speeds it along like a fresh-blowing westerly. It may be science lite, but out of thin air, Ms. Walker conjures marvelous shapes and forms.
—The New York Times
Publishers Weekly

Most of the time we hardly notice that we're moving through air. But when a storm system whips it into a whirling mass that grows into a tornado or a hurricane, then the air around us makes headlines. Science consultant Walker (Snowball Earth) presents a lively history of scientists' and adventurers' exploration of this important and complex contributor to life on Earth, from Galileo's early attempts to show that it has weight to the explorations by 20th-century scientists Oliver Heaviside and Edward Appleton of the ionosphere, which acts as a giant mirror bouncing radio waves from one side of the globe to another. Walker provides readers with easy-to-follow discussions of the science behind the discovery that carbon dioxide levels are rising exponentially; the theoretician who left her computer for Antarctica and discovered a huge ozone hole created by chlorofluorocarbons; why hurricanes form only in the tropics and why global warming may lead to more violent storms. She goes far afield at times, spending too much time on the Van Allen belts, for instance, but readers will find this informative book to be a breath of fresh air. (Aug.)

Copyright 2007 Reed Business Information
Library Journal

Beginning with a gripping prolog that recalls an air force captain's daring parachute jump from the edge of space, science writer Walker (Snowball Earth) chronicles the lives and work of scientists who have endeavored to answer this question: What isair? From the first experiments by Galileo to the studies of modern scientists looking at the ozone layer, readers catch the excitement that is borne of ideas, trial and error, and the fitting together of puzzle pieces that lead to an understanding of our world. Walker's writing is itself a breath of fresh air, clear and clean. She brings a new perspective to centuries-old stories of wonder and discovery and sheds light on the personalities of the 19th and 20th centuries who have also contributed to the world's body of knowledge. Witty and full of fascinating information, this is a captivating book that is very highly recommended for undergraduate libraries and public libraries of all sizes.
—Denise Dayton

Kirkus Reviews
The fascinating story of earth's atmosphere, filled with fresh and lively biographical sketches of intrepid explorers of the natural world from Galileo to James Van Allen. Walker, a consultant to New Scientist magazine, brackets her narrative with two opposite journeys through the atmosphere: Air Force test pilot Joe Kittinger's extraordinary plunge from the edge of hostile space to the New Mexico desert in 1960, and the ascent of a weather balloon in Greenland in 2006. Between is a fascinating account of the very nature of the protective blanket that surrounds our earth. Walker, who has a Ph.D. in chemistry, writes with a pop journalist's eye for the personal detail that makes a character come alive. There is no chalk dust in her description of Galileo's measurements of the weight of air; Torricelli, Boyle and Hooke's experiments with air pressure; Priestley and Lavoisier's work with gases; or Joseph Black's discovery of carbon dioxide. Who knew that Hooke was "an irascible hunchback, a hypochondriac with a caustic wit and a terrifying manner"? Or that Priestley discovered how to make fizzy drinks for his houseguests? The author also considers the motion of air, from Columbus's utilization of the trades and Westerlies to carry him to the New World to the calculations of an American farmer who worked out that the winds of the northern and summer hemispheres move in mirror image. A chapter on ozone features the discoverer of the ozone layer, Irish scientist W.M. Hartley, and the American inventor of the CFC Freon, Thomas Midgley, as well as the scientists who discovered what CFCs were doing to the earth's ozone layer. She concludes with Van Allen and his discovery of the radiation beltsthat bear his name. Throughout, the link between changes in the earth's life-generating, life-preserving atmospheric shield and global warming are deftly woven into the narrative. Science made accessible and entertaining. Agent: Michael Carlisle/InkWell Management
From the Publisher


"I never knew air could be so interesting."—Bill Bryson, author of A Short History of Nearly Everything

"[Walker provides] counter-intuitive delights . . . This is a fabulous introduction to the world above our heads."—Daily Mail on Sunday (London)

author of A Short History of Nearly Everything Bill Bryson

"I never knew air could be so interesting."
author of The Beak of the Finch Jonathan Weiner

"An Ocean of Air is a fascinating book. The subject is hot, the science is cool, and Gabrielle Walker's style is lighter than air. Warmly recommended."
author of Stiff Mary Roach

"Who knew air could be so interesting? Like the scientific mavericks she profiles, Gabrielle Walker had the freshness of vision to realize that within its presumed-nothingness lay the most fascinating, profound revelations about life on earth. This is science writing at its best: clear, witty, relevant, unbelievably interesting, and just plain great."

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Product Details

Houghton Mifflin Harcourt
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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, desiring 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.”
           Back in Galileo’s time, notions about air were similarly hazy. Most people accepted the idea put forward by Aristotle in the fourth century b.c. that everything in the world was made up of four elements: earth, air, fire, and water. Earth and water were obviously pulled downward by gravity. Fire was obviously weightless. But air was the problem child. Was it heavy enough to be dragged to the ground, light enough to rise like flames do, or did it simply ignore Earth’s gravitational tug and hover?
           Galileo believed that air is heavy and had set about testing his idea. The experiments he performed were typically ingenious. First, he took a large glass bottle with a narrow neck and a tight leather stopper. Into this stopper he inserted a syringe attached to a bellows and by working vigorously managed to squeeze two or three times more air into the bottle than it had previously contained. Next, he weighed the glass bottle most precisely, adding and subtracting the finest of sand to his scales until he was satisfied with the answer. Then, he opened a valve in the lid. Immediately, the compressed air rushed out of its confinement, and the bottle was suddenly a handful of grains lighter. The air that had escaped must account for the missing weight.
           This showed that air is not the insubstantial body we usually take it for. But now Galileo wanted to know how much air corresponded to how many grains of sand. For that he would somehow need to measure both the weight of the escaping air and its volume.
           This time, he took the same glass bottle with its long, narrow neck. However, instead of pumping it full of extra air, he forced in some water. When the bottle was three-quarters full of water, its original air was squeezed uncomfortably into a quarter of its original space. Galileo weighed the bottle accurately, opened the valve, allowed this pressurized air to escape, and then weighed the bottle again to find out how much air he had lost. As for the volume, Galileo reasoned that the portion of air that had been forced to leave the bottle had been pushed aside by the water he had squeezed in, so the volume of air that had fled must be exactly the same as the volume of water that remained. All he had to do was pour out the water and measure its volume and voilà, he had found the weight for a given volume of air.
           The value Galileo came up with was surprisingly large: Air seemed to weigh as much as one four-hundredth the weight of an equivalent amount of water. If that doesn’t sound like much, consider this. Picture a particular volume of air for a moment—such as the “empty” space inside Carnegie Hall in New York. How heavy would you expect that amount of air to be? Would it weigh ten pounds? Or a hundred? Or maybe even five hundred?
           The answer is somewhere in the region of seventy thousand pounds.
           The weight of air is so extreme that even Galileo didn’t see the whole story. He never considered the question of how we can shoulder such a crushing, overwhelming burden, for the simple reason that he didn’t realize the air above us is still heavy. He had measured the weight of air in his bottle, but he was convinced that the moment this air was released back into its natural element, the sky, it immediately ceased to weigh anything at all.
           Galileo believed that our atmosphere as a whole is incapable of pushing. It was one of the few occasions when the great man was wrong.
           In spite of the Church’s opposition Galileo finished his manuscript—and published it. After fruitless efforts to convince publishers in Florence, Rome, and Venice to defy the Inquisitors, Galileo finally smuggled the manuscript out to a printer in the Netherlands. Four years later, as he approached the end of his life, a few copies began filtering back to Italy. Each bore a disingenuous disclaimer by Galileo himself, who wrote how astonished he was that his words had somehow found their way to a printer’s in spite of his obedience to the Papal diktat.
           And although Galileo was wrong about the way our air behaves aloft, the experiments his great work contained would influence two very different people to discover the truth.

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 or mailed to the following address: Permissions Department, Harcourt, Inc.,  6277 Sea Harbor Drive, Orlando, Florida 32887-6777.

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What People are saying about this

Bill Bryson
"I never knew air could be so interesting."--(Bill Bryson, author of A Short History of Nearly Everything)
Mary Roach
"Who knew air could be so interesting? Like the scientific mavericks she profiles, Gabrielle Walker had the freshness of vision to realize that within its presumed-nothingness lay the most fascinating, profound revelations about life on earth. This is science writing at its best: clear, witty, relevant, unbelievably interesting, and just plain great."--(Mary Roach, author of Stiff)
Jonathan Weiner
"An Ocean of Air is a fascinating book. The subject is hot, the science is cool, and Gabrielle Walker's style is lighter than air. Warmly recommended." --(Jonathan Weiner, author of The Beak of the Finch)

Meet the Author

GABRIELLE WALKER has a PhD in chemistry from Cambridge University and has taught at both Cambridge and Princeton universities. She is a consultant to New Scientist, contributes frequently to BBC Radio, and writes for many newspapers and magazines. She is also the author of four books, including An Ocean of Air and Antarctica. She lives in London.

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