Nuclear explosion

[rwh]

On some pictures of nuclear explosions there are lines that usually run straight up from the ground. One of the coolest pictures I've seen had these trails originating from each side of the explosion and crossing each other behind the mushroom cloud. So what are these things? How long do they last? And does the blast wave from the explosion dissipate them?

[Gonzolo]

They are independent smoke trails. Analysing how they dissipate gives information on the blast waves.

[hitssquad]

They are independent smoke trails. Analysing how they dissipate gives information on the blast waves.This is not quite correct. The photographs that are analyzed are taken before either the shock wave or wind reaches the smoke columns. What is analyzed is the refraction error created by viewing the yet-unaffected smoke columns through the shock circle:
http://www.vce.com/atomictrails.html

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The progress of the shockwave was then followed by observing the "hooks" in the rocket trails at the shock front. These hooks are due to the change in the index of refraction of the air at the shock front.
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[Gonzolo]

They are independent smoke trails. Analysing how they dissipate gives information on the blast waves.

My post should have the word "dissipate" replaced by "look". Never knew about the so-called hooks. Thanks for the link.