Windswept_ The Story of Wind and Weather - Marq de Villiers [19]
It was left to the ever-practical Frenchman Antoine-Laurent Lavoisier, to demolish the phlogiston theory entirely. He was the first to understand the significance of Priestley's writing on oxygen, and he disproved phlogiston by showing that oxygen is required for combustion, as well as for rusting and respiration. Lavoisier, who began his career in the Royal Gunpowder Administration in Paris, is best known for his synthesis of chemical knowledge in his Traite elementaire de chimie, in which for the first time the modern notion of elements was laid out systematically.
In the revolutionary spirit of the time, Lavoisier made a symbolic break with the theory by burning all the books on the subject he could lay his hands on.
And in the other spirit of the time, though a political moderate, he died on the guillotine during the Terror, in 1794.6
Lavoisier was influenced by Robert Boyle (1627-1691), who had made precise measurements in studying the relationship between volume and pressure of gases. In the Sceptical Chymist Boyle questioned Aristotle's view of the four elements and proposed matter was composed of tiny particles, therefore becoming the first modern to synthesize the two Greek notions of the universe. He was followed by Joseph Black (1728—1799), who discovered carbon dioxide in 1750 and showed that it was produced in combustion, human breath, and fermentation; and by Henry Cavendish (1731-1810), who found that common air was made up of nitrogen and oxygen in a 4:1 ratio. Carbon dioxide might still be called fixed air, hydrogen inflammable air, and nitrogen dead air, but oxygen was no longer called dephlogisticated air, and Cavendish's mix was about right.
So now we knew what air was.
V
But we didn't yet know what the atmosphere was. That had to wait for modern science, for the atmosphere is much more complex than was thought even a hundred years ago. Air, with its patented mix of gases and in its various degrees of thinness and density, is one thing, but the atmosphere is also made up of bands of radiation, clouds of ionized gases, zone layers, and swirling magnetic fields, all of which impinge on our weather and our winds, and thus on us, down here at our little intersection of atmosphere and lithosphere where living things make their home.
The first complication is that the atmosphere has layers, according to the density of the air. In the conventional taxonomy, weather occurs and we live in the troposphere, a layer of air ranging from the earth's surface, where it is densest, to somewhere between 5 miles at the poles and a little more than 10 miles at the equator. Within the troposphere, the air gets colder the farther away from the earth it is, which is why airplanes flying at around 20,000 feet usually push through air whose temperature is well below zero, even at equatorial latitudes. (The range is generally thought of as "earth-normal" to —6o° Celsius). Despite the commonsensical observation that winds are largely horizontal, which is how we perceive them, the prevailing movement of air within the troposphere is actually vertical, in what are now called Hadley and Ferrel cells.
The atmosphere, showing the approximate ranges of the major layers, the aurora regions (in the thermosphere, at left), and the orbiting altitude of the space shuttle.
Above the troposphere is a thin layer of stable temperatures generally called the tropopause, to distinguish it from the next layer up, the stratosphere, which itself reaches to around 31 miles from the earth's surface. Temperatures