<p>I think the best model we could use for this is nuclear test fallout, whose dispersion was monitored quite extensively.  It's very, very dependent on weather patterns at altitude.</p>

<p>For example, the <a href="https://en.wikipedia.org/wiki/Castle_Bravo#Fallout" rel="nofollow noreferrer">Castle Bravo test</a> mushroom cloud reached at altitude of about 40km and hence hit the Jet Stream.  In addition to this the wind speeds at lower altitudes were higher than ground speeds and this was not checked for, so the combination of factors spread the fallout downwind about 280 miles (about 430 km) in about 16 hrs.  This was one reason for the irradiation of many people.</p>

<p>What these tests and other nuclear incidents show us is that material ejected into the high atmosphere can remain there a long time, even circling the globe <a href="https://www.washingtonpost.com/national/as-fukushima-fallout-circles-the-globe-nuclear-sleuths-sift-it-for-clues/2011/03/30/AFfnQBHC_story.html?utm_term=.9674a018df89" rel="nofollow noreferrer">like traces from Fukushima</a>.</p>

<p>In theory trace particles from a meteor could remain in the upper atmosphere for days, months, even years.  Most would be expected to fall within days, however.</p>

CC BY-SA 3.0
2017-11-21T09:27:31.310Z
That's a nice deductive answer.  I'll add a related point on Tephra, where the very small particles (.01 mm and less) can stay in the air (by this article) sometimes for two or three years.   http://www.geo.mtu.edu/volcanoes/hazards/primer/tephra.html
userLTK
CC BY-SA 3.0
2017-11-21T15:03:13.397Z
The only problem with this analysis is that it makes assumptions about the resulting particle sizes as a meteor disperses.
Carl Witthoft
CC BY-SA 3.0
2017-11-21T16:43:43.643Z
@CarlWitthoft If you're suggesting that after breaking up in the atmosphere nothing remains but gas (which seems to be your implication) I'd need some reasonable argument to justify that - it sounds like a more drastic assumption to me.
StephenG - Help Ukraine
CC BY-SA 3.0
2017-11-21T16:45:40.623Z
Stephen, not gases, but perhaps particles of both mass and density small enough that even mid-to -upper atmospheric densities and wind strenghts are sufficient to make the "airborne half-life" on the order of years.
Carl Witthoft
CC BY-SA 3.0
2017-11-21T16:50:56.033Z
@CarlWitthoft Hmmh.  Have you a basis for estimating such a size and/or whether this isn't the case with material from fallout ?  Just trying to tease out as solid a basis as possible for your suggestion.
StephenG - Help Ukraine
CC BY-SA 3.0
2017-11-21T18:47:36.530Z
My point is that neither of us has a basis, and without such, your answer may be misleading.
Carl Witthoft
CC BY-SA 3.0
2017-11-21T03:45:34.940Z
2017-11-21T03:45:34.940Z
StephenG - Help Ukraine
<p>I know that meteors that We see as shooting stars travel tens of thousands of kilometers per hour and are tiny as a grain of sand, but after hitting the atmosphere and burn I suppose that its ashes would touch the ground at some point. How long does it take? Can it be measured or observed?</p>

CC BY-SA 3.0
2017-11-20T15:08:21.143Z
Meteors that burn up do so at an altitude of the order of 100 km, depending on [their incoming speed](http://earthsky.org/space/at-what-altitude-do-meteors-become-incandescent). Thus, their ashes will be scattered over thousands of square kilometers, making it impossible to find.
pela
CC BY-SA 3.0
2017-11-20T19:25:11.953Z
It will also depend on the angle at which they enter the atmosphere.
Phiteros
CC BY-SA 3.0
2017-11-21T15:02:04.413Z
I'm voting to close this question as off-topic because the assumption is wrong.  No solid-state particles of  measurable size need survive.
Carl Witthoft
<gravity><planetary-atmosphere><meteor>
How much time does it take for a meteor (shooting star) to touch the ground after its combustion?
Daniel Ibaseta
# How much time does it take for a meteor (shooting star) to touch the ground after its combustion?

(Asked by: username_0 on 2017-11-20)

I know that meteors that We see as shooting stars travel tens of thousands of kilometers per hour and are tiny as a grain of sand, but after hitting the atmosphere and burn I suppose that its ashes would touch the ground at some point. How long does it take? Can it be measured or observed?

**Tags:** gravity, planetary-atmosphere, meteor
> **Comments:**
> **username_1**: Meteors that burn up do so at an altitude of the order of 100 km, depending on [their incoming speed](http://earthsky.org/space/at-what-altitude-do-meteors-become-incandescent). Thus, their ashes will be scattered over thousands of square kilometers, making it impossible to find.  
> **username_2**: It will also depend on the angle at which they enter the atmosphere.  
> **username_3**: I'm voting to close this question as off-topic because the assumption is wrong.  No solid-state particles of  measurable size need survive.  

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## 1 answers

### Answer by username_4 on 2017-11-21. Score: 3 | Accepted answer

I think the best model we could use for this is nuclear test fallout, whose dispersion was monitored quite extensively. It's very, very dependent on weather patterns at altitude.

For example, the [Castle Bravo test](https://en.wikipedia.org/wiki/Castle_Bravo#Fallout) mushroom cloud reached at altitude of about 40km and hence hit the Jet Stream. In addition to this the wind speeds at lower altitudes were higher than ground speeds and this was not checked for, so the combination of factors spread the fallout downwind about 280 miles (about 430 km) in about 16 hrs. This was one reason for the irradiation of many people.

What these tests and other nuclear incidents show us is that material ejected into the high atmosphere can remain there a long time, even circling the globe [like traces from Fukushima](https://www.washingtonpost.com/national/as-fukushima-fallout-circles-the-globe-nuclear-sleuths-sift-it-for-clues/2011/03/30/AFfnQBHC_story.html?utm_term=.9674a018df89).

In theory trace particles from a meteor could remain in the upper atmosphere for days, months, even years. Most would be expected to fall within days, however.

> **Comments:**
> **username_5**: That's a nice deductive answer.  I'll add a related point on Tephra, where the very small particles (.01 mm and less) can stay in the air (by this article) sometimes for two or three years.   http://www.geo.mtu.edu/volcanoes/hazards/primer/tephra.html  
> **username_3**: The only problem with this analysis is that it makes assumptions about the resulting particle sizes as a meteor disperses.  
> **username_4**: @CarlWitthoft If you're suggesting that after breaking up in the atmosphere nothing remains but gas (which seems to be your implication) I'd need some reasonable argument to justify that - it sounds like a more drastic assumption to me.  
> **username_3**: Stephen, not gases, but perhaps particles of both mass and density small enough that even mid-to -upper atmospheric densities and wind strenghts are sufficient to make the "airborne half-life" on the order of years.  
> **username_4**: @CarlWitthoft Hmmh.  Have you a basis for estimating such a size and/or whether this isn't the case with material from fallout ?  Just trying to tease out as solid a basis as possible for your suggestion.  
> **username_3**: My point is that neither of us has a basis, and without such, your answer may be misleading.  

---

