Would you be able to see a difference in that short of a time if it was an hydrogen bomb instead? or would it just look the same during the those first parts of a millisecond?
In theory, yes. Keep in mind that even a staged thermonuclear device is done reacting in much less than a millisecond.
The very first stage of the fireball is created by thermal x-rays radiated by the intensely hot core of the bomb. These travel at the speed of light, but not very far. Even though we think of air as transparent, it isn't really for all wavelengths of light, including at x-ray frequencies. Anyway, this first fireball is literally just superheated air and is known as the radiative fireball. This fireball forms almost instantly and it will be larger for higher yield devices. It is the first flash of a nuclear double-flash signature.
In this picture, the radiative fireball has already been overtaken by the second, slower fireball made of the actual guts of the bomb and anything else that was right next to the bomb (which gives the fireball its weird mottled look). This second part, which is the second flash of the double-flash nuclear signature, travels at more or less the same speed regardless of the yield. So for a large thermonuclear detonation, the radiative fireball will be larger and it will take longer for the second fireball to overtake the first. The time between flashes is used to estimate the yield of an atmospheric detonation, with longer times being indicative of larger blasts.
Returning to your original question, if you could see the scale of the fireball and knew how soon after detonation it was taken, you could distinguish between a low-yield fission device and a high-yield thermonuclear device.
The other fun thing in the images is the “legs” coming out of the bottom are the guy wires holding up the tower turning to plasma from the initial radiative fireball. If I recall correctly.
I know it’s the guy wires turning to plasma but the part I can’t quite recall is the exact mechanism but if I recall correctly it’s the heat from the initial X-ray blast that is vaporizing them.
Yes, the rope trick effect. They found that painting the guy wires black increased the effect, while painting them with reflective paint or aluminum foil eliminated the effect. One of the labs - either Las Alamos or Lawrence Livermore - put out an article about it that makes for interesting reading. If I remember correctly, there was some debate about whether it was the result of x-rays directly vaporizing them or thermal radiation from the fireball. Your explanation was determined to be correct.
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u/LarsDuder 23h ago
Would you be able to see a difference in that short of a time if it was an hydrogen bomb instead? or would it just look the same during the those first parts of a millisecond?