All you have to do is check social media to find out who lives in the American Southwest. People in Arizona and the surrounding states are posting their local temperatures and pictures of frying eggs and melting candles. The National Weather Service has “excessive heat warnings” out for triple digit temperatures that have lasted a week already.

What’s behind the high-temperature summer kickoff? An increasingly common meteorological phenomenon dubbed the “heat dome.” Basically, heat domes are created when a high-pressure system forms in the mid- to upper-atmosphere; the air pressure pushes warm air down towards the surface and traps it there, resulting in higher — often much higher — than normal temperatures. The term first came into heavy use in 2011, according to a New York Times investigation into its growing popularity, although many meteorologists quibble with its descriptive accuracy. As Oklahoma City weatherman Gary England told the Times, “I’ve used ‘heat dome’ off and on over the years, but I think it’s a little bit misleading; it’s not shaped like that.”



“Heat bubble,” actually better describes the shape, according to experts, but it also lacks the apocalyptic connotations that many suffering through temperatures over 100º probably feel is warranted.

Getting the name correct is little comfort to those who can’t escape the heat. And these heat domes are becoming more frequent as the years go by. Read more about them at Atlas Obscura. Oh, and happy Summer Solstice, everyone!



(Image credit: Flickr user Graeme Maclean)