Word Count

Writers Talk About Writing

When Lightning Strikes, What Does Air Do?

Stan Carey, a professional editor from Ireland, writes entertainingly about the English language on his blog Sentence First. Here a children's book about weather leads Stan to ponder which English words best describe what happens to air when it is heated by lightning.


Burst after burst the innocuous thunders brake.
— Robert Southey

John Farndon's Weather: How to Watch and Understand the Weather and its Changes is a charming children's book published as part of DK's Eyewitness Explorers series. On page 47 I read the following line:

Thunder is the sound of air bursting as it is heated rapidly by lightning.

The description struck me as strange, because I'm used to thinking of superheated air not bursting but expanding rapidly or violently to form a pressure wave that causes the sound of thunder. There is a sense in which burst can mean expand rapidly, but it more usually means something like explode or tear, or surge in more figurative contexts. That is, it tends to imply a physical membrane or boundary that is opened, ripped, broken, split, shattered, and so on; there is usually a sense of boundary-breaking, albeit one that varies greatly in intensity and abstraction.

Some examples will help us examine the semantic constellation of burst. Tomatoes that are bursting with ripeness burst in our hands or in the microwave. A tree's roots burst slowly through concrete; the sun bursts through the clouds; swollen rivers burst their banks; the Hulk's clothes burst at the seams; a sportsman makes a burst of speed to burst through the opposing defence; a busy room fills to bursting (point), whereupon the nearest person to the door might burst it open. The recurring sense of rupture or explosivity is evident in this word map from the Visual Thesaurus:

People burst into song when their hearts are bursting with joy, and they burst into shivers if a window bursts open on a cold day; they burst into tears if their hair bursts into flame, and they burst into laughter (or "burst out laughing") when a burst of amusing data enters their minds. We hear bursts of conversation and bursts of gunfire. We see bursts of activity, such as sudden bursts of rain or sunshine. When air or another gas bursts, it is usually from something, such as a tyre, bubble, balloon, nail gun, or a mouth in the act of blowing out a candle (though a puff is usually enough).

The sound of thunder can be a clap, crack, peal, snap, roll, or rumble; each term has its own nuances. But to explain the sound as air bursting is, I think, inferior to expanding rapidly or some such phrase that would minimise the possibility of fuzzy or misleading interpretations. Especially since many people — not least children — are afraid of storms, and air bursting carries more alarming connotations than does air expanding (slight semantic overlap notwithstanding).

Am I being foolish, fussy, or fair? Have I made a storm in my afternoon teacup?


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Stan Carey is a scientist turned freelance editor from the west of Ireland. He shares his fascination with language, words and books on his blog, Sentence first, and on Twitter. Stan has a TEFL qualification, a history of polyglottism, and a lifelong love of stories and poetry. He writes articles about the English language for Macmillan Dictionary Blog. Click here to read more articles by Stan Carey.

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Comments from our users:

Monday May 17th 2010, 6:19 AM
Comment by: Mark A. L.
I agree that the image of bursting air is either difficult or frightening to imagine. It sounds apocalyptic! "The elements shall melt with fervent heat!" (II Peter 3:10).

If I remember correctly, there is one barrier that the air is breaking as it makes thunder: the sound barrier. That does provide some connection to the idea of bursting, but I would not say that the air itself is bursting. I'm a musician, not a scientist, so someone can correct me on all this.

ML
Monday May 17th 2010, 9:27 AM
Comment by: Paula B. (Blaine, MN, MN)
I love the way you have written up the sense extensions of *burst* in the two paragraphs flanking the VT web. I teach ESL to university level international students and am intrigued by the idea of teaching sense extensions for vocabulary development. Visual thesaurus offers nice snapshots of these, but writing these up in paragraph form adds great support.
Monday May 17th 2010, 10:33 AM
Comment by: Don H. (Antioch, CA)Top 10 Commenter
Perhaps you are a little fussy, Stan. The online diction gives the definition: "To come open or fly apart suddenly or violently, especially from internal pressure. To explode."

I actually like "burst" much more than "expanding rapidly." To me, at least, there was no misunderstanding. "Burst" is one of the right words for the thing being described....
Monday May 17th 2010, 10:41 AM
Comment by: Richard W. (AUSTIN, TX)
The lightning itself is certainly a "burst," as it equalizes the polarized charges of positive and negative, plus, the lightning is super hot causing the air to explode (burst), and what we hear is the sound wave created by the heat that bursts the air next to the lightning. Without the bursts would we hear anything?
Monday May 17th 2010, 1:21 PM
Comment by: Stan Carey (Galway Ireland)Visual Thesaurus Contributor
Mark: It's a question of suitability rather than correctness. Burst can mean "expand rapidly", so its use in the book is defensible. But because it's more generally understood as rupturing or tearing a boundary, I think its use in the book fails to adequately convey the sense of rapid expansion, which is what the air is doing. As a scientist and musician, I'm still a bit puzzled!

Your example of the sound barrier is interesting. The very term recalls the "membrane or boundary" I mentioned, and the phenomenon is sometimes accompanied by a very eye-catching clouds that the plane (or whatever) ruptures as it breaks the barrier. To quote the article I linked to: "A sudden increase in pressure and temperature causes surrounding air to expand violently at a rate faster than the speed of sound, similar to a sonic boom. The shock wave extends outward for the first 30 feet (10 m), after which it becomes an ordinary sound wave called thunder."

Paula: Thank you. I'm glad you found the prose helpful, or potentially so for your students. I had to edit those paragraphs, because there were far too many examples in the first draft! Burst is one of those words with a great many figurative and idiomatic uses.

Don: Perhaps I am! Some days and some moments are fussier than others. Would you prefer expand violently to expand rapidly? Rapid might be a bit tame for such a powerful event, though these qualities are relative.

Richard: Lightning can readily be described as a burst, but that's a separate matter. I remain unconvinced that "air bursting" is the best way to describe thunder in a children's science book.
Monday May 17th 2010, 1:36 PM
Comment by: Samuel E.
I certainly agree with most, if not all, of the comments, but I think that the point was missed that Weather is a children's book. In this sense, I feel that burst is an appropriate word to desscribe what happens to the air as it is superheated by the discharge of lightning. I am not suggesting that the book is "dumbed down" for the intended audience, nor would I advocate such a thing. I merely suggest that burst is appropriately descriptive, if not scientifically correct.
Monday May 17th 2010, 3:17 PM
Comment by: sherry I. (denver, CO)
Visual Thesaurus, so much information, so many articles, so many people, so many opinions, so much fun!
Monday May 17th 2010, 4:00 PM
Comment by: Don H. (Antioch, CA)Top 10 Commenter
Right! What Sherry said...!
Monday May 17th 2010, 10:51 PM
Comment by: Wightly (Frederick, MD)
I agree with Samuel E. that "air bursting" is appropriate in this context. After all, we have something "bursting into flames" and "bombs bursting in air". What we SEE in the last two cases IS a "rapid or violent expansion" of something.
Tuesday May 18th 2010, 9:29 AM
Comment by: Jane B. (Winnipeg Canada)Top 10 Commenter
You can also be 'bursting with pride' over something that the child with that book does.

And if you are, and say it, prehaps that would mitigate any harmful effects that the 'burst' might have.

I think it's an expressive word for children and that the more detailed expressions wouldn't have that impact.

Thunder does sound like an explosion, so it's an appropriate expression. It need not result in fear of storms, but more delight depending on how a parent handles it.

If the child has heard thunder, the word 'burst' is just a description, something like a balloon bursting. He or she would make the connection easily.

Me? I'd be more inclined to have problems. I'd be the one thinking of my universe coming apart at the seam with each clap!
Tuesday May 18th 2010, 3:50 PM
Comment by: Stan Carey (Galway Ireland)Visual Thesaurus Contributor
Thank you Samuel, Sherry, Don, Wightly, and Jane for your additional comments. Jane's insight in particular has made me wish I could be a child again, momentarily, in order to read the line afresh.

My age, reading history, and educational background all contribute to my interpretation of the word burst, and I can't undo any of these factors. But all the responses have helped me consider the (modest) problem in a different way. I've decided that I was being slightly foolish, definitely fussy, and I don't know how fair.

I'd also like to apologise for the typo in my previous comment, when I wrote "accompanied by a very eye-catching clouds". Please ignore the "a"!
Tuesday May 18th 2010, 5:46 PM
Comment by: Caren B.
Burst is best so far.
Saturday June 5th 2010, 2:55 AM
Comment by: John F.
Just one further point, Stan, since you have bowed so graciously to Jane’s defence of the word ‘burst’. It seems to me you might find it easier to reconciling your ‘adult’ use of the word ‘burst’ if you went into the science a little more thoroughly. Jane says, to create leeway for using the word ‘burst’, that thunder sounds like an explosion. But it’s not just a loose simile; it is very accurate.

You suggested ‘expanding rapidly’ but of course expansion, fast or slow, has no sound. What thunder, a bag bursting, a balloon bursting – and an explosion – all have in common is that air or gases expand so rapidly that they break through the sound barrier, and the sonic boom is the bang you hear in each case, whether it's the boom of a bomb or a clap of thunder

So ‘bursting’ is not just a wonderfully evocative image for children; it is much, much more scientifically precise than the pseudo-scientific sounding (and soundless!) ‘expanding rapidly’ you originally suggested as an alternative.
Monday June 7th 2010, 7:13 AM
Comment by: Stan Carey (Galway Ireland)Visual Thesaurus Contributor
John: I was under the impression that thunder was the sound of the wave that followed the initial sound-barrier-breaking burst or expansion. (As you can see, I'm becoming reconciled to burst.) A sound wave doesn't have to be supersonic to be audible. Even moving my hand through the air creates a modest noise. So I don't think "rapidly expanding air" is pseudo-scientific at all, nor is it soundless.
Monday June 7th 2010, 5:49 PM
Comment by: Jane B. (Winnipeg Canada)Top 10 Commenter
Gee, Stan, I was always taught that thunder was Rip Van Winkle bowling up in heaven... Sigh! Another dream burst! LOL
Thursday August 5th 2010, 7:27 PM
Comment by: Oleksandr R. (Saskatoon Canada)
What about a conception of a momentarily superheated air (plasma), bursting out of a bolt channel into a cold surraunding air?

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