Book Review: Gabrielle Walker, An Ocean of Air : Why the Wind Blows and Other Mysteries of the Atmosphere

Book Review

Given that it's a book about science and nature, you'll be happy to hear that there are about a dozen servings of people-stories for every serving of hard science. (I can't expect all of you to be geeks like me :-)

An Ocean of Air : Why the Wind Blows and Other Mysteries of the Atmosphere is the new book by chemist and science journalist Gabrielle Walker.

The real hero of the book is the blanket of air, the world's relatively paper-thin layer that does so many things to keep us alive. As with other aspects of our natural world, our understanding of it began in a heap of misconceptions and superstitions, out of which the climb was slow.

Galileo, famous to us as the gravity experimenter who came before Newton, and as the troublemaker who said that the earth revolves around the sun, did make one serious error. He denied the possibility of air pressure. He didn't know that the atmosphere pushes. He thought that a vacuum sucks. He had it exactly backwards. Torricelli was motivated to conduct the experient that would expose Galileo's error, and he did, and it did. [pages 7-8]

But it was Boyle who first realized, and proved, that when a barometer measures air pressure, what it's really detecting is the weight of the air on top of it. Try to visualize a column of air that's as wide as the barometer, and extending all the way upward to the vacuum of space -- what would it weigh? [17-18]

The discovery of oxygen was another big obstacle. It didn't seem obvious to anyone back then that there's something in the air that breathing animals and burning lamps must be extracting from the air. However, there was an apparent connection between air and heat. Priestly upheld the old assumption that heat, which flows from the hot to the cold regions of any material, is some sort of fluid moving through it. That imaginary fluid, which we now know doesn't exist, was given the name phlogiston. Therefore, what we now call oxygen, Priestly reasoned, would seem to be air that can be "dephlogisticated". No, said Lavoisier -- air is a mixture rather than a single substance, and an element that he called oxy-gene is one of its parts. [38-42]

About the Author

Gabrielle Walker is an award-winning science writer who has a Ph.D. in chemistry from Cambridge and has presented many programs for BBC radio. She has served as a climate-change editor at Nature, features editor at New Scientist, and visiting professor at Princeton University. She lives in London.

- From the Publisher

It was Lavoisier who replaced the hocus-pocus with real science. He conducted an experiment inside an air-filled jar. Inside of it was a substance burning as it rested on a scale. The scale tipped, showing that burning made the substance gain weight. However, the weight of the entire jar was the same as before. Something in the air (it was oxygen, of course) had to be combining with a substance when it burns. [39]

I found a bit of humor in Lavoisier's tendency to consider Priestly quite illogical and irritating. Priestly tried hard, perhaps too hard, keeping himself so busy with doing experiments that he didn't pause frequently enough to think about which experiments would be the really useful ones to perform. [38]

The discovery of the "Mirror in the Sky" [title of chapter 6] is another delightful story which turns out to have oxygen in the center of it. After Marconi invented the wireless telegraph, communication with ships at sea became possible for the first time. It was a surprise to find that the horizon was no obstacle, that the signals seemed to curved around the Atlantic ocean in a way equivalent too climbing a mountain with a height of 150 miles [166-167]. Later on the public, while being entertained by AM radio broadcasts, was delighted by that same ability of radio waves apparently to bend around a curved world. At night New Yorkers can hear AM stations from Chicago very clearly. But the waves couldn't really be bending -- they had to be reflecting. There had to be some kind of "mirror" up there. Oliver Heaviside, who studied many of the properties of electromagnetic waves and electronic components, gets remembered for his 1902 prediction that the atmosphere must have an ionized (electrically charged) layer. In 1924 Appleton experimentally verified Heaviside's prediction, with the help of the staff at BBC radio. The people at the radio station agreed to help him with his experiment by broadcasting varying frequencies. [175, 191-192]. Today we realize that the ionisphere is produced because ultraviolet light and x-rays from the sun kick electrons out of the oxygen molecules.

All this has gone on too far without mentioning love and sex, so let's do that now. No one ever said that sexual reproduction was a perfectly symmetrical relationship, but here's another asymmetry to ponder. The egg spends most of its time in storage and isolated, so its mitochondria don't get damaged by free radicals. The sperm's has to travel, so its mitochondria are severely damaged -- but then they are not subsequently used for anything. If there were only one sex, the stored egg would have to age. Having two sexes is the reason the aging process doesn't begin until the egg is fertilized. The author concludes: "Hence the troubles, and glories, of romantic relationships between men and women are born in the chemistry of oxygen." [49]

There is more to air than oxygen, of course. Understanding the movement of air, the currents and the turbulence, was another achievement. Meteorologist William Ferrel studied the combined effect of warm air rising and the earth rotating. The book contains two diagrams showing how the movement of air forms into the trade winds and westerlies, which always move in particular directions [102, 112] Wiley Post, the first pilot to make a solo flight around the world, encountered apparent "rivers of air" [author] encircling the globe in the stratosphere, which he called "high winds", and which we today call the jet stream. [120] The only World War II fatalities to occur on the mainland of the U.S., six in total, took place in Oregon in 1945, after the Japanese government attached explosives to balloons and allowed the jet stream to carry them 6,000 miles. [121]

News reports occasionally describe several atmosphere-related safety hazards that humanity faces in the long term. The book clarifies several of them. One of these is the greenhouse effect that raises world temperatures. The author points out the involvement of carbon dioxide there. [75-76] Radiation from the sun is another hazard. There are two types of solar radiation, high frequency electromagnetic waves (ultraviolet and x-rays) and high-speed subatomic particles. The ozone layer (chapter 5) shields us from the waves. but we must heed "the hole story" [129]. The artificial gas Freon became available in 1930. Its associated family of gases, called chlorofluorocarbons (CFCs), were believed to be harmless, and were used in products as diverse as hair spray and refrigerators [135]. The author describes the tendency of the chlorine in CFCs to turn ozone into oxygen, in other words, 2O₃ --> 3O₂. [143] Another beneficial shield from solar radiation is earth's magnetic field. A diagram illustrates the field deflecting the solar wind (a stream of high velocity particles) so that it won't cook us. [230]

Our long human history has taken place in a very thin layer. In the last century people first acquired the ability to visit the space outside of it. The Soviet Union placed the satellite Sputnik into orbit in 1957. The "Sputnik cocktail" became a popular drink in America. It was made from vodka and sour grapes. [198]

A skilled popular science writer, Gabrielle Walker has produced a book that is as entertaining as it is informative.

Walker is also the author of the 2004 book, Snowball Earth : The Story of a Maverick Scientist and His Theory of the Global Catastrophe That Spawned Life As We Know It .

Book review August 11, 2007 by Mike Lepore for crimsonbird.com