zlacker

I saw part of the burst and to me it was immediately clear what it was. Also, the timing of the boom arrival helped determine the distance with good precision.

Thoughts, 'WOW', 'COOL', 'Did somebody film that??', and, of course, the rest of the workday was not very productive. It was nice to see that so much footage made.

One thing footage doesn't show is, however, the heat: the radiation was intense and open parts of the skin did feel hot, like , REALLLY BURNING HOT. Had it lasted longer, there would be burns on everybody.

>>Andrew+(OP)
I've seen estimates of the Chelyabinsk energy yield at about 500 kT TNT equivalent. How that was distributed as light, shock wave, and thermal energy (latter coupled with light) has been something I'd wondered at, and your comment on the heat is interesting.

I'd think that a larger impactor or one that survived further into Earth's atmosphere (and closer to the surface) might have changed that experience markedly. You're informing my own advice-to-self as to how to respond should I see a very large airburst at some point. "Stay away from glass" was already part of that, as well as "expect the shockwave after about 90 seconds". I think I'll add "avoid direct thermal exposure if it looks to be large" to the list.

If you've not already seen the Sandia Labs modelling based on the 1908 Tunguska event, the shockwave dynamics suggest to me why and how the multiple shockwave arrivals at a given point on the ground occur:

https://newsreleases.sandia.gov/releases/2007/asteroid.html

Particularly this simulation: http://www.sandia.gov/videos2007/2007-6514Pfire.hv1.1.mpg

>>dredmo+3f
"Resist the urge to stare at it through the window"

>>HPsqua+Jz
The one reason Halifax has such a large amount of expertise on eye surgery was people not resisting that urge.

>>dredmo+3f
Nukemap has settings for airburst height (under "advanced options"): https://nuclearsecrecy.com/nukemap/

For a 10mt explosion at 20km height it shows a third degree burn radius of 27km. Chelyabinsk was ~0.5kt at 29km. Larger objects are expected to penetrate further into the atmosphere before exploding: https://en.wikipedia.org/wiki/Meteor_air_burst

I'm not sure how much time you'd have to evaluate size or distance, videos of Chelyabinsk show it pretty bright just a second or two after becoming visible. Length of infrared exposure determines severity of burn, so reacting early is helpful.

>>jacque+Yr1
From 1917?

>>HPsqua+Jz
"Do not look into laser with remaining eye."

"Do not gaze upon meteorite armageddon through window with remaining face."

>>jacque+Yr1
That was 191x. And still translates to experience/quality/clustering of eye surgery there?

I'm unaware of something like that in locations which suffered from large explosions around a similar timeframe.

>>LargoL+CY1
There's apparently some literature on the topic:

https://www.researchgate.net/publication/5633081_The_Halifax...

https://scholar.google.com/scholar?q=eye%20surgery%20halifax...

>>dredmo+3f
If you are serious about that, you'll need to retrain one of your instincts — there is a nearly reflexive response to orient towards a new or bright flash of light. In normal situations, this is highly adaptive. However, in raare events like meteors, nuclear or other really large explosions, it results in literally frying the retinas before the viewer has time to sort out what is happening, nevermind judging whether it "looks to be large".

You'll need to retrain your instincts to instantly close your eyes and flinch away in response to bright light, then judge the "looks to be large (or not)" through your closed eyelids. This should work fine as I remember reading that some observers of the Trinity nuclear test blast saw the bones of their hands through their closed and covered eyes...

Alternatively, make a habit of wearing welding glasses with 100% UV protective glass that will auto-darken to Shade 14++

&yes, those Sandia Labs simulations are really amazing!

>>toss1+Ef2
There's some trainability.

If you're close enough to a fireball that you're instantly incinerated, you might as well just enjoy the show. There's nothing you can do.

If you're within the zone of survivability, then there's cause to take action, and responses over seconds, minutes, and hours can make a difference. A 20--30 mile airburst gives 2--3 minutes before he

The prompt heat flash lasts several seconds. Ducking and sheltering quickly behind any shading barrier will provide protection. Infrared is no penatrating radiation. And bollides as blackbody emitters release mostly IR and visible light. Short-term flash-blindness, likely, permanent blindness ... probably not?

Blast effects lag blast by seconds to minutes. A 20--30 mi altitude bollide burst (32--48km) gives 2--3 minutes before the blast will hit.

Fragments might be another risk. Again, they'll lag considerably and arrive with fairly low terminal velocity for any likely impactor.

TL;DR: Killing effects cover several modalities and don't arrive instantaneously or simultaneously.

>>dredmo+1o2
Oh, yes, there absolutely is trainablity, you just need to do the training as it's against 'natural' orientation instincts.

Totally agree on the survivability. While most ppl just immediately think 'it's a nuke/meteorite, you're just fried', even a quick look will show that the lower effects zone is at least 10x the area of the 'you're fried' zone.

So yes, just instantly closing your eyes & looking away, stepping away from the window, behind a tree or lamppost, etc. can do a lot in the first 5 seconds, then using the next 10sec that get behind something to be on the leeward side of the shockwave, and you'll be way ahead of the situation. Probably best measure is to avoid important cities.