A mighty wind

Q: How long has “derecho” been a meteorological term in the US? And how did the Spanish word for “right” come to mean a line of severe thunderstorms? I’m a weather observer, but I hadn’t heard the usage until this summer.

A: The weather term “derecho” first showed up in English in the 1880s, but it was rarely used, even by meteorologists, until the 1980s, according to a paper by Robert H. Johns on the history of the term.

Johns, a meteorologist who specializes in severe convective storms and tornadoes, says the term refers to “widespread straight-line damaging winds associated with lines of thunderstorms.”

The National Oceanic and Atmospheric Administration describes a “derecho” as “a widespread, long-lived wind storm that is associated with a band of rapidly moving showers or thunderstorms.”

“Although a derecho can produce destruction similar to that of tornadoes, the damage typically is directed in one direction along a relatively straight swath,” NOAA says.

Gustavus Detlef Hinrichs, a professor of physical sciences at the University of Iowa, coined the weather term “derecho” in the late 19th century to distinguish storms with winds blowing straight from tornados with circular winds.

Hinrichs first used the term in 1883 at a meeting in Minneapolis of the American Association for the Advancement of Science, according to a brief history by Ray Wolf of the National Weather Service Forecast Office in Davenport, Iowa.

But Hinrichs didn’t use the word in writing until 1888, when he published a paper, entitled “Tornadoes and Derechos,” in the American Meteorological Journal.

The English term is derived from the Spanish adjective derecho, which means straight as well as right. Spanish seems an apt source, since it has also given English the word “tornado.”

The etymology of “tornado,” though, is appropriately twisty. It apparently comes from tronado, Spanish for “storm,” but the spelling reflects confusion with tornado, Spanish for “turned,” according to John Ayto’s Dictionary of Word Origins.

The term “derecho” doesn’t appear yet in the Oxford English Dictionary, but a July 25, 2012, posting on the OxfordWords blog says that “only relatively recently has it risen to any kind of prominence.”

In the posting, Ammon Shea, a consulting editor for American dictionaries at Oxford University Press, says the term “gained in popularity after the eastern US states experienced a particularly devastating storm at the end of June.”

In another indication that the term is relatively new in popular usage, we could find an entry for it in only one standard dictionary, the new fifth edition of The American Heritage Dictionary of the English Language.

The earliest mention of the term in the New York Times is from an Aug. 27, 1995, article about a storm that killed four campers and a motorist in the Adirondacks: “It is called a derecho by the weather connoisseurs and its fury is unrelenting.”

Although the term appeared occasionally in the Times over the next decade and a half, it didn’t show up in large numbers until a storm in the Mid-Atlantic region on June 29, 2012, killed 22 people and left more than 4 million without power.

As a July 2, 2012, article in the Times put it, “Millions of people learned a new word over the weekend: ‘derecho.’ It was not a happy lesson.”

That probably explains why you just began noticing the term this summer.

Check out our books about the English language