Return to Index

Nuclear Bomb

Nuclear Bomb - The Explosion

The distinctive double flash of a nuclear detonation. 

Let's take a moment to talk about what happens during the first few milliseconds when a nuclear explosion happens. When the explosion begins, the device itself quickly goes to a temperature of about ten million kelvins. The X-rays and ultraviolet waves emitted heat the air within a few meters of the device to a temperature of about one million kelvins, which makes it extremely incandescent and causes an incredibly bright flash. Meanwhile, inside that cloud of bright gas, a shockwave expands, pushed by the explosion itself. Inside that shockwave, everything is a plasma, where the atomic particles are actually dissociated. Plasmas are opaque, because they absorb electromagnetic radiation at all frequencies. As that shockwave expands, it overtakes those first few meters of incandescent air, and once it does, its opacity actually shades it like a curtain. From there, the shockwave expands outward spherically; and as the plasma thins and diminishes it becomes increasingly transparent, allowing the expanding fireball to shine forth with its full brilliance. Thus, when a nuclear explosion happens, we actually get a double flash. The larger the yield, the longer the space between the flashes; ranging from 30 milliseconds for the smallest devices to half a second for larger ones.