Eyewitness Accounts of the Explosion at Trinity on July 16, 1945

I viewed the test, with the Coordinating Committee expedition, from a point about twenty miles away. At the instant of the explosion I was looking directly at it, with no eye protection of any kind. I saw first a yellow glow, which grew almost instantly into an overwhelming white flash, so intense that I was completely blinded. There was a definite sensation of heat. The brilliant illumination seemed to last for about three to five seconds, changing to yellow and then to red; at this stage it appeared to have a radius of about twenty degrees. The first thing I succeeded in seeing after being blinded by the flash looked like a dark violet column several thousand feet high. This column must actually have been quite bright, or I would not have been able to distinguish it. By twenty or thirty seconds after the explosion I was regaining normal vision. At a height of perhaps twenty thousand feet, two or three thin horizontal layers of shimmering white cloud were formed, perhaps due to condensation in the negative phase of the shock wave. Some time later, the noise of the explosion reached us. It had the quality of distant thunder, but was louder. The sound, due to reflections from nearby hills, returned and repeated and reverberated for several seconds, very much like thunder. A column of white smoke appeared over the point of the explosion, rising very rapidly, and spreading slightly as it rose. In a few seconds it reached cloud level, and the clouds in the immediate neighborhood seemed to evaporate and disappear. The column continued to rise and spread to a height of about twice the cloud level. There was no appearance of mushrooming at any height. A smoke cloud also was spreading near ground level.

The grandeur and magnitude of the phenomenon were completely breath-taking.