Course Hero. "A Short History of Nearly Everything Study Guide." Course Hero. 18 Jan. 2018. Web. 13 Dec. 2018. <https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/>.
Course Hero. (2018, January 18). A Short History of Nearly Everything Study Guide. In Course Hero. Retrieved December 13, 2018, from https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/
(Course Hero, 2018)
Course Hero. "A Short History of Nearly Everything Study Guide." January 18, 2018. Accessed December 13, 2018. https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/.
Course Hero, "A Short History of Nearly Everything Study Guide," January 18, 2018, accessed December 13, 2018, https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/.
Bryson moves from the subject of the land and sea to discuss the atmosphere. It is useful, he points out: keeping us warm, deflecting ultraviolet rays, keeping raindrops from "pound[ing] us senseless." He describes it as having four different parts. The troposphere contains the majority of the heat and oxygen animals and plants need for life and is only 10 miles thick at its widest point. The remainder of the atmosphere is characterized by a series of levels with changing temperatures, some hotter and some colder. The most amazing aspect of the atmosphere is its lack of depth; it extends upward for only 120 miles. Wind, Bryson says, is the air's way of trying to "keep things in balance" as air flows from areas of high to low pressure.
The astronomer Edmond Halley and another Englishman, George Hadley, were among the first to recognize the atmosphere is constantly adjusting to achieve equilibrium. The atmosphere is heated in the tropics, flows to Earth's poles, then sinks and returns to the tropics. A French engineer, Gustave-Gaspard de Coriolis, quantified these interactions and gave them the name "Coriolis effect."
Meteorology as a science didn't take off until the 19th century, in part because the measurement of weather required the measurement of temperatures. Accurate thermometers were not invented until the early to mid-18th century. English pharmacist Luke Howard is generally claimed as the modern father of meteorology and is best known for naming the four types of clouds: stratus, cumulus, cirrus, and nimbus.
Bryson discusses the water cycle: rain falls and returns to the atmosphere in the form of evaporated molecules. Clouds, however, account for only about 0.035% of Earth's freshwater. Rather, says Bryson, "Oceans are the real powerhouse of the planet's surface behavior." Oceans hold and transport heat, influencing climate. In addition, marine organisms capture carbon in the atmosphere and lock it in their shells, keeping it from building up in the atmosphere as dangerous "greenhouse" gases. Humans disrupt this carbon cycle by putting extra carbon into the air. Some scientists believe these disruptions will reach a critical threshold where trees and other plants die, exponentially adding to the amount of carbon in the atmosphere. While Bryson notes Earth will probably recover, "the last time this happened, it took a mere sixty thousand years."
Bryson shows changes to the atmosphere and atmospheric circulation have a great impact on the terrestrial world below. Despite being extraordinarily thin when compared to the depth of Earth, the atmosphere—together with the ocean—largely regulates Earth's temperature. As a result, the atmosphere is critical for the sustainability of life on Earth.
Bryson's description of the atmospheric system provides a scientific context for global climate change. Bryson is not an alarmist but dryly notes the time frame during which Earth could correct a carbon imbalance is 60,000 years. He allows readers to draw their own conclusions about this fact.