When I lived in Grand Beach, Michigan, on the other side of Lake Michigan, I could usually see the three tallest buildings in Chicago from the beach at the end of my street. On rare occasions, I got the entire skyline. But at 43 miles away and zero elevation, it’s not actually possible to see that far, given the curvature of the earth. Someone at sea level can typically see three miles to the horizon. So how was I seeing Chicago?

Turns out I wasn’t — not directly, anyway. I was looking at the result of an optical phenomenon called atmospheric refraction, or “looming,” which is “the appearance of distant objects that are usually hidden by the convexity of the earth’s surface,” according to Andrew Young, a professor of astronomy at San Diego State University. The short explanation is that variations in density of the earth’s atmosphere cause light to bend. “If the looming is not very strong, people across the lake can see the tops of the tallest buildings,” Young says. But if it’s stronger — when the water is colder than the air, as it usually is in the spring — “they can see the whole skyline.”

Whatever it was, the sight of Chicago made me homesick. So I moved back here, where I can see the skyline for real — no looming necessary.

Send your questions about the Chicago area to emcclelland@chicagomag.com.