Ground Zero: Standing Under A Nuclear Explosion

[Ism]

So, these boys had already seeded their offspring prior to the explosion I assume?

Yeah, one would hope.

So, ok, maybe the explosion itself didn't cause the sky to go black. Slightly less awesome, but still cool, nevertheless.

I don't know for sure because film from that day is different from film and video stock of today, but my guess is that the brightness of the explosion caused the iris to constrict and let less light in, making the sky turn from blue to black. You can get the same effect by taking a picture of a bare light bulb with your camera...the rest of the room will appear darker than it really is.

Yeah, overexposure would explain a darker sky post-explosion, at least for the eyewitness.

 

[Mal12345]

I don't want to spoil the fun, but it looks like there are two camera's, neither of them change the color of the sky, the one pointing towards the explosin appears to have a shader lens of sorts as to try and record the flash the the explosion in proper contrast. Otherwise the explosion might not be visible as the light of the explosion would exceed the recording capacity of the camera, and would just appear white.

So, these boys had already seeded their offspring prior to the explosion I assume?

You didn't spoil anybody's fun. Because the on-the-scene narrator said that the sky was black. It looks more like a shade of dark blue. I'm not talking about the sky color toward the horizon, only the sky in the immediate vicinity of the blast.

But the main problem with your theory is that the sky remained a dark blue color after the bright light of the explosion had faded. It did appear bright white for about 2 seconds at 1:10, but the sky looked purple. At 1:14 it takes on the dark appearance. 37 seconds later it still looks dark. The orange ring appears at this point and the narrator says it is orange. So there is no special lens at work.

 

[Mal12345]

Yeah, one would hope.

So, ok, maybe the explosion itself didn't cause the sky to go black. Slightly less awesome, but still cool, nevertheless.



Yeah, overexposure would explain a darker sky post-explosion, at least for the eyewitness.

Was it the lens in his cyborg eye that made it appear dark? Ok, lesson's over, you kids can go play now.

 

[Ism]

Was it the lens in his cyborg eye that made it appear dark? Ok, lesson's over, you kids can go play now.

Nonono, lol. Sorry. I meant. Well. Gish said this:

There are many eyewitness accounts of nuclear explosions that describe the sky as being dark,

FMW's explanation could account for the eyewitnesses that Gish mentioned. That's what I meant by eyewitnesses, lol, it just wasn't clear.

 

[EffEmDoubleyou]

Yeah, overexposure would explain a darker sky post-explosion, at least for the eyewitness.

I'm talking about overexposure in the camera causing the dark sky. The personal view of the eyewitness isn't related to what's shown on the film.

 

[Ism]

I'm talking about overexposure in the camera causing the dark sky. The personal view of the eyewitness isn't related to what's shown on the film.

Ah, ok! The iris thing threw me off, but I was skimming, so I didn't pick everything up.

 

[Mal12345]

I'm talking about overexposure in the camera causing the dark sky. The personal view of the eyewitness isn't related to what's shown on the film.

Orange smoke ring on video, orange smoke ring according to eyewitness. Dark sky according to video, dark sky according to eyewitness. Seems related.

 

[sprinkles]

Orange smoke ring on video, orange smoke ring according to eyewitness. Dark sky according to video, dark sky according to eyewitness. Seems related.

Yeah, strangely enough though it should be bright and colorful when detonated at 10,000 feet because there is still quite a lot of atmosphere around, above and below it. It's different if it is at 100,000 feet or higher because the atmosphere is less dense.

Basically what happens is in the first pulse, the fireball sets off a lot of X rays that are incredibly hot and the shockwave compresses the atmosphere, which 'sucks up' the invisible X rays and cools them off making a lot of incandescent light. Since all this energy is running at the speed of light, it outruns the shockwave, but then it slows down and the shockwave catches up and recompresses it again, making a second incandescent pulse.

Really all of this stuff should be very bright, not dark. So there has to be another reason it happens.

 

[Mal12345]

Yeah, strangely enough though it should be bright and colorful when detonated at 10,000 feet because there is still quite a lot of atmosphere around, above and below it. It's different if it is at 100,000 feet or higher because the atmosphere is less dense.

Basically what happens is in the first pulse, the fireball sets off a lot of X rays that are incredibly hot and the shockwave compresses the atmosphere, which 'sucks up' the invisible X rays and cools them off making a lot of incandescent light. Since all this energy is running at the speed of light, it outruns the shockwave, but then it slows down and the shockwave catches up and recompresses it again, making a second incandescent pulse.

Really all of this stuff should be very bright, not dark. So there has to be another reason it happens.

Hot Xrays?

The brightness of the explosion - which by the way was at 18,000 feet although the video states 10,000 at the beginning - intensifies the blueness of the sky by atmospheric scattering of more of the blue spectrum of the light emanating from the explosion. I agree that the height of the explosion - whether 10,000 or 18,000 ft - has a lot to do with it.

 

[sprinkles]

Hot Xrays?

The brightness of the explosion - which by the way was at 18,000 feet although the video states 10,000 at the beginning - intensifies the blueness of the sky by atmospheric scattering of more of the blue spectrum of the light emanating from the explosion. I agree that the height of the explosion - whether 10,000 or 18,000 ft - has a lot to do with it.

Yes, hot X rays. Nuclear blasts produce black body (or near it) radiation, which is dependent on heat, going from a very deep orange, nearly red, at 1000 kelvins and a very bright, almost light sky blue, at 100,000 kelvins. The temperatures can go into the millions of kelvins which goes beyond the visible electromagnetic spectrum and into UV and X ray.

Edit: now that I think of it, this would pass the deep blue and purple spectrum so you probably would get some really dark blue light at some point. Maybe that is the explanation after all.

Edit edit: also interestingly this makes a nuclear blast similar to a small temporary star in certain ways.