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Airing Out the History of Earth's Atmosphere

Air may seem weightless, colorless and, at times, inconsequential, but the invisible blanket that covers the world has heft.

Thanks to Galileo, scientists now know that concertgoers at New York's Carnegie Hall sit under 70,000 pounds of air each night. Breathing air for a year is like being hit with 10,000 chest X-rays. And air can act like a giant mirror that bounces radio waves from one side of the world to another.

From Galileo to global warming and windstorms, author Gabrielle Walker plunges into the Earth's atmosphere, exposing its layers and complex history in An Ocean of Air. Walker, who has a doctorate in chemistry, brings a seemingly bland substance to life, carefully explaining the invisible ocean around us.

In particular, three historical characters catch Walker's attention. William Ferrel, a West Virginia farm boy, made random observations on prevailing winds and helped explain the rotation of the Earth and the movement of air across its surface. Oliver Heaviside was an eccentric, self-taught scientist who discovered that an electrical layer in the sky (now called the Heaviside Layer) helps move radio signals across Earth. And Norweigian scientist Kristian Birkeland studied the global pattern of electrical currents.

But An Ocean of Air also takes time to answer the basics like why the wind blows and what makes the Northern Lights twinkle. Andrea Seabrook spoke with Walker about this life-sustaining substance.

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