Fenyman in his book describes what he saw through his eyes when the first nuclear bomb was tested:
Time comes, and this tremendous flash out there is so bright that I duck, and I see this purple splotch on the floor of the truck.
I said, “That’s not it. That’s an after-image.” So I look back up, and I see this white light changing into yellow and then into orange.
Clouds form and disappear again–from the compression and expansion of the shock wave.
Finally, a big ball of orange, the center that was so bright, becomes a ball of orange that starts to rise and billow a little bit and get a little black around the edges, and then you see it’s a big ball of smoke with flashes on the inside, with the heat of the fire going outwards.