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As a metaphor for absence and nothingness, air has performed admirably for centuries. It has pulled off one of the great con jobs in human history, concealing endless complexities behind its bland, transparent facade. Layer by layer, from the ionosphere to the Earth’s surface, Gabrielle Walker exposes the Earth’s atmosphere for what it is, a restless, electrically charged, dynamic superhero, entrusted with the sacred mission of protecting our planet, nurturing life and even, when looked at from a certain angle, making love possible.
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Lars Klove for The New York Times

"An Ocean of Air" by Gabrielle Walker.

AN OCEAN OF AIR

Why the Wind Blows and Other Mysteries of the Atmosphere

By Gabrielle Walker

Illustrated. 272 pages. Harcourt. $25.

Ms. Walker, a chemist by training and a science journalist by profession, finds that angle in “An Ocean of Air,” her perkily popular take on air, wind, atmosphere and the scientists who unraveled their mysteries, from Galileo onward. It starts with oxygen, creator and destroyer, foundation of the atmosphere, the revolutionary element that quickens life and hastens death through its ferocious reactivity, and requires two sexes. Oxygen-burning, ever-aging mitochondria from the male expend energy seeking out cool, unaged mitochondria in the female egg, which guarantee that the human embryo’s biological clock starts at zero. Romance is in the air.

Like Dava Sobel in “The Planets,” Ms. Walker writes for a general audience and seems to assume something close to scientific illiteracy in her readers. There is plenty of gee-whiz and tee-hee in her merry tale, a colorful blend of anecdote, personality and pure science explained in the simplest terms. Every fact is chased with a sweetener to make it go down a little easier, and each turn in the narrative ends with a cliffhanger.

At times Ms. Walker can be absolutely shameless in her efforts to keep readers on the edge of their seats. A straightforward account of Marconi’s experiments with radio waves leads right into a taut recounting of the Titanic’s last hours as experienced from the ship’s telegraph room. This is completely beside the point but forgivable, first, because it is undeniably stirring, and second, because Ms. Walker has put the reader on an addictive drip-feed of asides and digressions

She starts early. After carefully explaining Galileo’s efforts to measure the weight of air, Ms. Walker leans forward from her lectern, as it were, and poses a simple but intriguing question: How heavy is it? Well, imagine an empty space, say, the inside of Carnegie Hall. Take a guess. Ten pounds? A hundred? Five hundred? Try 70,000 pounds.

The fun facts keep on coming. Simply breathing air for one year is equivalent to being bombarded by the radiation from 10,000 chest X-rays. It’s that reactive oxygen again. Every year green plants convert carbon dioxide into 100,000 million tons of plant material, otherwise known as food, using up 300 trillion calories of energy from the sun, which is 30 times the energy consumption of all the machines on Earth.

Somewhat less dramatically, John Tyndall, the Victorian scientist who first discovered the link between carbon dioxide and infrared radiation, drew such large crowds to his lectures at the Royal Institution in London that Albemarle Street had to be made a one-way thoroughfare — Britain’s first — to accommodate the carriage traffic.

Tidbits like this should not disguise that 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 ties her discoveries to personalities, and three of them obviously capture her heart and imagination. The first is William Ferrel, a poor, mostly self-taught farm boy from West Virginia who collated random observations on prevailing winds and used them to explain the relationship between the rotation of the Earth and the movement of air across its surface.

Ms. Walker’s second hero, Oliver Heaviside, is almost too good to be true, from his name to his eccentricities. “Tales of his oddities were legion,” Ms. Walker writes. “He furnished his rooms with blocks of granite; he dyed his hair black and then wore a tea cozy on his head until it was dry; he kept his nails exquisitely manicured and painted them cherry red.” He also explained what Marconi never understood, that radio signals can overcome the curvature of the Earth even though they travel in a straight line because an electrical layer in the sky, now known as the Heaviside layer, acts as a mirror, bouncing the waves back to Earth.

The third star in Ms. Walker’s twinkling constellation is Kristian Birkeland, a Norwegian scientist whose fascination with the northern lights led him to a discovery that, had anyone paid attention, would have made it less of a surprise when American scientists found that space is radioactive.

Ms. Walker 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.