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Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

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Re: Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

#61

Post by IAmGraydon »

jcranmer wrote: post #39
aaron695 wrote: post #28

Earlier quoted context omitted.

I'd like to know why it initially sounds like fireworks https://twitter.com/HeshmatAlavi/status/1290683991369097216 [camera operator probably would have died in the second blast] Is that what set it off? Or is that what ammonium nitrate sounds like burning?

From what I understand, ammonium nitrate isn't particularly flammable, until it gets hot--then it gets explosive. Furthermore, ammonium nitrate conflagrations tend to give a distinctive reddish smoke cloud. The cloud accompanying the big explosion has a very distinct red tint to it, indicating that it's a result of the ammonium nitrate going off. That before it doesn't, which suggests that the ammonium nitrate wasn't…

Ammonium nitrate does not release nitrogen dioxide unless it undergoes high-order detonation.

Re: Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

#62

Post by IAmGraydon »

shadowprofile77 wrote: post #42

Nitpicking here maybe but this does not look like a 3 kiloton blast to me. Neither the size of the core explosion or the apparent shock wave damage correspond to that magnitude from a surface blast. Guessing here but I'd say closer to 2 kilotons at most. Amazingly, the massive, hollow grain silo right next to the detonation itself remained standing afterwards.

It’s not a 3kt blast. Not even close.

Re: Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

#63

Post by kleton »

raverbashing wrote: post #58
WalterBright wrote: post #52

Earlier quoted context omitted.

My fluid mechanics prof told the class that a scientist in the 1940's published the yield of the Hiroshima bomb. Since this was top secret, he got investigated. But he showed how the yield could be calculated from the film of the explosion - how fast the blast radius expanded. So I imagine the yield of the Beirut explosion could be calculated the same way from the video.

There's a story about Feynman estimating yield by dropping pieces of paper and seeing how far they'd travel in the shockwave

Feynman told that story about Fermi.

Re: Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

#64

Post by jwilliamson »

jcranmer wrote: post #55
justinclift wrote: post #49

Earlier quoted context omitted.

On that note, I wonder how the ships / watercraft in the area handled it. Overturned/sunk/? :(

Naval ships are generally spaced at about "I can see the nearest ship to me in my binoculars"-distances. To give a sense of scale, the USS Washington firing on the IJN Kirishima in the Second Battle of Guadalcanal is reckoned as one of the shortest-range engagements in WWII... at about 5km. That said, the remaining ships in the area were the surviving Japanese destroyers, and destroyers closing in closer to ships wou…

Some WW2 battles were fought at significantly shorter ranges than that. Just in the Malta campaign, at Cape Passero the Italians closed to around 1700m before opening fire. In the attack on the Tarigo convoy, the British closed to 1800m before opening fire and approached as close as 50m to the Italian ships.

Re: Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

#65

Post by justinclift »

jcranmer wrote: post #55
justinclift wrote: post #49

Earlier quoted context omitted.

On that note, I wonder how the ships / watercraft in the area handled it. Overturned/sunk/? :(

Naval ships are generally spaced at about "I can see the nearest ship to me in my binoculars"-distances. To give a sense of scale, the USS Washington firing on the IJN Kirishima in the Second Battle of Guadalcanal is reckoned as one of the shortest-range engagements in WWII... at about 5km. That said, the remaining ships in the area were the surviving Japanese destroyers, and destroyers closing in closer to ships wou…

Sorry, bad wording on my part. I was more wondering about ships/watercraft around the port for this current explosion.

Re: Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

#66

Post by KMag »

IAmGraydon wrote: post #59
KMag wrote: post #57

Note that the distinctive orange color is probably a large volume of nitrogen dioxide at pretty high concentration. If it was an ammonium nitrate explosion, the orange cloud supports the idea it was accidental. The explosion would have been easier to set off and more powerful had there been a fuel (or more fuel) mixed with the ammonium nitrate.

Why do you think that the release of NO2 makes it an accident? Nitrate based high explosives only release NO2 during an actual high-order detonation. Ammonium nitrate does this with or without sensitizers such as fuel oil.

A mixture close to a neutral oxygen balance (stochiometric mixture) would consume much of the N02 and have a much less brilliantly orange plume. Though, point taken that sensitization happens much before reaching a neutral oxygen balance.

Re: Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

#67

Post by raverbashing »

kleton wrote: post #63
raverbashing wrote: post #58

Earlier quoted context omitted.

There's a story about Feynman estimating yield by dropping pieces of paper and seeing how far they'd travel in the shockwave

Feynman told that story about Fermi.

Ah you're right!

Re: Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

#68

Post by burfog »

aaron695 wrote: post #27
netsharc wrote: post #20

Earlier quoted context omitted.

See, again with the expectations. If every big event requires a link to in-depth analysis on the front page of a news site, they'd need to have a small font size and a 16K monitor... And you'd complain that it's not in the corner you looked.

If you think this shouldn't be the clear headline, then I guess we consider news to be different things. I'll go back to reading next in my feed how George R R Martin is racist because he mispronounced someones name (Not an article in the Guardian, and the Guardian's coverage is exceptional for Beirut compared to others like CNN or Fox) [edit] Does the media not care about the largest peacetime explosion in a capital…

The news is way worse than that. A couple notable things they mostly buried just this past week:

The George Floyd bodycam video leaked out, destroying the BLM narrative (see https://news.ycombinator.com/item?id=24046940 for DailyMail). ABC doesn't cover it. CBS and NBC edit out "Stop resisting". Youtube suppresses it from trending. NBC even had privately seen the bodycam video a month prior, leaving them no excuse for stoking violence across the country.

We finally got evidence (both flight logs and a victim statement) that a former US president was at Epstein's island.

Both of those are far more important to Americans than a big explosion in a far off city.

Re: Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

#69

Post by grogenaut »

aaomidi wrote: post #37
actuator wrote: post #36

Earlier quoted context omitted.

From the videos I have seen the Tianjin fireball seemed to rage even for a longer duration. In the Beirut one maybe because of daylight, fire is not visible after the big blast. I wonder what would cause that difference, the Beirut one supposedly had more material as well.

Longer fire = less energy for explosion?

High explosives burn too fast for regular flames and suck the oxygen out for subsequent burning. Though you can definitely see fire in the first few frames. https://en.m.wikipedia.org/wiki/Red_Adair got famous for putting out oil well fires with high explosives. Explosives on burn that fast due to their chemical structure not because of free oxygen in the atmosphere. So if you see a fireball, the explosion has slowed way down.

People are used to huge fireballs in movies because they just aerosolize gasoline or others for that effect. Also it's a lot safer than high explosives. High explosives are dangerous.

An goes at around 10,000 feet/second or 6,800mph or 10,900 kmh.

In those videos when the white large cloud comes out (likely some form of the air being hyper compressed by the shockwave and forced faster than the speed of sound) I was like drop Camera get behind wall nooooooowwww. Or we'll keep camera it may be useful in about 45 minutes.

Re: Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

#70

Post by jeffbee »

aaron695 wrote: post #41

I should just pre-flag this comment, so feel free. But Hezbollah use Ammonium Nitrate and could use the other small explosives stored near by. I think under current rules being actioned if there was intel people were stealing from the factory it would be considered a legitimate target. The question would be, would the analysis of intel be good enough to know exactly what was stored there and if it is clearly not an a…

Everyone knew what was stored there because it was abandoned in the port six years ago and sitting there ever since.
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