The x-rays are mainly produced during the ionisation of the bomb material itself, and is the majority of the initial energy produced (though there's also gamma rays and flying neutrons and fun stuff such as that); the reactions with the air molecules aren't high-energy enough to produce anything with wavelengths shorter than UV. The x-rays fly out and react with the air around it and produce a shockwave in that air. The remaining ionised matter from the bomb creates a second, faster internal shockwave that eventually overtakes the outer shockwave, and is what produces much of the initial UV energies. And as the different waves and particles spread outwards, they collide with other particles and produce other, lower-energy things. What other things are produced immediately afterward and when and how they are produced depends on where the bomb is when it detonates.GlytchMeister wrote:Well, that was generated by the flash, I think, rapidly sun-bleaching everything with line-of-sight to the detonation. And the flash, I think, came from the immense energy release heating and ionizing the air into plasma which then generated all of the X-rays and stuff.
All that electromagnetic radiation is just part of what would result from such an enormous energy dump - except the flash would last a lot longer in castela’s case, if she so chose.
In low-atmosphere detonations, you even get to have two flashes because the combined shockwaves are opaque to light, so you have the initial flash from detonation, then the second and longer flash once the shockwave has lost enough energy to become transparent and the inner incandescent fireball is visible again. By measuring the time between flashes, you can tell how powerful the bomb was. The second flash is when most of the thermal radiation is released.