By Sid Perkins
18 Miles
Christopher Dewdney
ECW Press, $17.95
How thick is Earth’s atmosphere? Sorry, that’s a bit of a trick question: Our planet’s air simply gets thinner with altitude, fading away to nothingness somewhere far above the height at which the lowest satellites orbit. It’s a fact, though, that 99 percent of Earth’s air lies below an altitude of 18 miles. Naturalist Christopher Dewdney uses that distance as the title of his latest book, which takes a deep dive into the science behind weather and climate.