Grammar Girl here. I'm In Jan Fogarty, your friendly guide to the English language.

Today we're going to talk about why heat is a wave but cold snaps. And then we'll look at what kind of reading is best if you want to improve your language skills.

Why do we call it a heat wave, but a cold snap?

That's the question listener Kate Moracle Townsend in, and it's an interesting one. If both

are weather events related to temperature, why the metaphor mismatch? Well, let's start with

heat wave. According to the Oxford English

dictionary, the term heat wave didn't appear in print until the late 1800s. So linguistically

speaking, it's pretty modern. It referred to an extended stretch of unusually hot weather,

typically several days in a row. The word wave was already used figuratively

to describe things that spread or surge, like a wave of emotion or a wave of illness. Scientists had

even started using wave to describe certain atmospheric patterns. So the image of heat arriving in a wave, rolling in, hanging around,

then receding, fit perfectly. It also distinguished it from the more generic hot spell,

which was commonly used before heat wave became standard. And being a grammar podcast,

we had to take a detour to check out what spelling had to do with a stretch of heat.

And it turns out the answer is nothing, because the two meanings of spell have completely

different origins in Old English and just happen to be spelled the same way now. Oh well.

Now, let's talk about cold snap. The word snap has a long history of describing things that are

sudden, sharp, and short-lived. You can snap your fingers. A twig can snap underfoot. Cold weather can snap at your

skin. The phrase cold snap has been around since at least the 1700s, and it vividly captures the

experience of an abrupt, intense burst of cold air. We do sometimes hear cold wave, especially

in meteorological contexts, but it tends to refer to a broader, longer-lasting event. Think of

multi-day deep freezes that affect large regions.

...