# Wiggly lines in nuclear bomb explosion

**URL:** <https://boards.straightdope.com/t/wiggly-lines-in-nuclear-bomb-explosion/340598>\
**Category:** Factual Questions\
**Created:** [January 19, 2006, 2:49am UTC](https://boards.straightdope.com/t/wiggly-lines-in-nuclear-bomb-explosion/340598 "2006-01-19T02:49:50Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![dgrev](https://avatars.discourse-cdn.com/v4/letter/d/839c29/32.png) [@dgrev](https://boards.straightdope.com/u/dgrev)\
**Post date:** [January 19, 2006, 2:49am UTC](https://boards.straightdope.com/t/wiggly-lines-in-nuclear-bomb-explosion/340598/1 "2006-01-19T02:49:50Z")

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Can someone explain what the wiggly diagonal lines are that are visible in  
so many pcitures of nuclear bomb explosions?

These lines are almost always at a 45° angle and appear evenly spaced.

They do not appear to originate from the centre of the blast.

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**Author:** ![antechinus](https://avatars.discourse-cdn.com/v4/letter/a/fbc32d/32.png) [@antechinus](https://boards.straightdope.com/u/antechinus)\
**Post date:** [January 19, 2006, 2:52am UTC](https://boards.straightdope.com/t/wiggly-lines-in-nuclear-bomb-explosion/340598/2 "2006-01-19T02:52:24Z")

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They are rocket trails. Used to give a sense of scale and measure the shock wave progress.  
[http://nuclearweaponarchive.org/Usa/Tests/SmokeTrails.html](http://nuclearweaponarchive.org/Usa/Tests/SmokeTrails.html)

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**Author:** ![Sublight](https://avatars.discourse-cdn.com/v4/letter/s/439d5e/32.png) [@Sublight](https://boards.straightdope.com/u/Sublight)\
**Post date:** [January 19, 2006, 2:54am UTC](https://boards.straightdope.com/t/wiggly-lines-in-nuclear-bomb-explosion/340598/3 "2006-01-19T02:54:10Z")

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Someone will probably have more detailed information, but basically those lines are smoke flares that are set off just before the explosion to act like lines on a ruler. The flares are set off at a known distance from the explosion (and from the observers), so that by looking at the photos of the explosion afterwards, one can make a good approximation of the size of the blast.

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**Author:** ![dgrev](https://avatars.discourse-cdn.com/v4/letter/d/839c29/32.png) [@dgrev](https://boards.straightdope.com/u/dgrev)\
**Post date:** [January 19, 2006, 3:22am UTC](https://boards.straightdope.com/t/wiggly-lines-in-nuclear-bomb-explosion/340598/4 "2006-01-19T03:22:51Z")

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Many thanks to those who replied.

I have a much better picture of the rocket trails than those shown  
in the link to the nuclear weapons archive. This pic was taken at  
Maralinga in Australia.  
However, I cannot see any way to post the pic to this forum, pity.

Thanks again people.

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**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\
**Post date:** [January 19, 2006, 3:26am UTC](https://boards.straightdope.com/t/wiggly-lines-in-nuclear-bomb-explosion/340598/5 "2006-01-19T03:26:42Z")

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You have to post the pic elsewhere, and can then provide a link to that posting here.

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**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\
**Post date:** [January 19, 2006, 10:29am UTC](https://boards.straightdope.com/t/wiggly-lines-in-nuclear-bomb-explosion/340598/6 "2006-01-19T10:29:22Z")

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A page with several photographs of the phenomenon mentioned at Maralinga can be found [here](http://nuclearweaponarchive.org/Uk/UKTesting.html)