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For Questions That Don't Merit Their Own Thread

Skyler4856

By Skyler4856
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JoeSchmuckatelli

JoeSchmuckatelli

Posted
Posted
11 minutes ago, AHHans said:

May I quote from the video description

Ah - thanks. 

I missed that. 

 

 

I hereby pronounce myself mollified. 

12 minutes ago, AHHans said:

Why

Um...

Because methane rain? 

https://earthsky.org/space/titan-saturns-moon-weather-seasons-methane-rain-storms/#:~:text=Lakes on Titan's surface are,Titan's weather and surface erosion.

Iron rain? 

'The iron vapor had mysteriously vanished as it moved across WASP-76b’s night side. To the researchers, this could mean only one thing: rain' 

https://www.google.com/amp/s/amp.theatlantic.com/amp/article/619198/

Based on stuff like that I presume that any liquid that can form a vapor will form clouds and thus... 

rain 

 

 

 

 

 

(although now I wonder what an 'Iron Rainbow' would look like ') 

 

 

 

https://www.metal-archives.com/bands/Iron_Rainbow/3887

... @kerbiloid

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AHHans

AHHans

Posted
Posted (edited)
1 hour ago, JoeSchmuckatelli said:

Um...

Because methane rain? 

[...]

Iron rain? 

I have two issues with that: one is that this is a good example of argument from anecdote or maybe appeal to probability. Just because it happens often, or even more often than not, doesn't mean that it always happens. And the other is that I don't believe that iron vapor condensing from a planet's atmosphere means that it rained down there. It could just as well have condensed at the surface of the planet, without forming droplets.

1 hour ago, JoeSchmuckatelli said:

(although now I wonder what an 'Iron Rainbow' would look like ') 

Considering that iron melts at 1811 K: it'll be orange, like a heavily dimmed incandescent light.

O.K. I'm stupid: how does the material used in iron or steel casting look [Edit: during the casting!]? Like that! :cool:

Edited by AHHans
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JoeSchmuckatelli

JoeSchmuckatelli

Posted
Posted
53 minutes ago, AHHans said:

anecdote or maybe appeal to probability

Okay - for fun - an anecdote about this:  I am a phenomenally intuitive person - so much so that I generally trust my intuition about people and things... because I am usually right.

This used to drive a friend of mine insane. 

He's the type who is so literally literal, he just cannot grasp or understand something being true in the absence of facts or proof.  He'd constantly ask me the 'why' of an opinion or for the data supporting an assertion, and when I would not (or could not) provide that information in a linear, progressive format, he would declare it false out of hand. 

And then be liquided when I turned out to be correct.

 

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AHHans

AHHans

Posted
Posted
4 minutes ago, JoeSchmuckatelli said:

I am a phenomenally intuitive person - so much so that I generally trust my intuition about people and things...

Same here . . . kind of. You shouldn't trust my opinion about people (I don't!), but about things (well, physics etc.) I'm usually right. Which can be quite annoying when other people start taking your word as gospel, i.e. don't bother checking if my guesses are actually right. Until you start writing a paper, then you actually have to prove that you are right.

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DDE

DDE

Posted
Posted
1 minute ago, kerbiloid said:

Does it differ from?

  Hide contents

BRDM-2_(1964)_owned_by_James_Stewart_pic

 

Flat hull = IEDs briefly turn them into ballistic missiles. Wasn't a consideration at the time. It's a major problem of BTRs as well, hence the rather narrow hull on the Boomerang.

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TheSaint

TheSaint

Posted
Posted
1 hour ago, DDE said:

And another small question: how do blast waves travel? Is a downwards-opening door on a MRAP a bad idea?

I would say no, it is not a bad idea. The primary threat MRAPs are designed to defend against are mines and IEDs, which are an explosive force directed from below. The strongest part of the door will be the hinge side, and if it is downward opening that is the side that will be closest to the blast, which means it will be harder for the blast to open the door or remove it from the vehicle. Also, if the door drops down it means you have gravity on your side when you're trying to open it; faster egress, less chance of the door jamming or sticking.

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JoeSchmuckatelli

JoeSchmuckatelli

Posted
Posted
39 minutes ago, TheSaint said:

I would say no, it is not a bad idea. The primary threat MRAPs are designed to defend against are mines and IEDs, which are an explosive force directed from below. The strongest part of the door will be the hinge side, and if it is downward opening that is the side that will be closest to the blast, which means it will be harder for the blast to open the door or remove it from the vehicle. Also, if the door drops down it means you have gravity on your side when you're trying to open it; faster egress, less chance of the door jamming or sticking.

Well - I was going to say this, but he's done an excellent job. 

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magnemoe

magnemoe

Posted
Posted
58 minutes ago, TheSaint said:

I would say no, it is not a bad idea. The primary threat MRAPs are designed to defend against are mines and IEDs, which are an explosive force directed from below. The strongest part of the door will be the hinge side, and if it is downward opening that is the side that will be closest to the blast, which means it will be harder for the blast to open the door or remove it from the vehicle. Also, if the door drops down it means you have gravity on your side when you're trying to open it; faster egress, less chance of the door jamming or sticking.

Good points also the door is also an ladder going down or up who they done, this is the driver's door he will not use that in combat except bailing out. 
 

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TheSaint

TheSaint

Posted
Posted (edited)
42 minutes ago, magnemoe said:

Good points also the door is also an ladder going down or up who they done, this is the driver's door he will not use that in combat except bailing out.

All the more reason to want it to open quickly and reliably, without the need for any sort of power.

Edited by TheSaint
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AHHans

AHHans

Posted
Posted (edited)
On 10/6/2021 at 3:30 AM, JoeSchmuckatelli said:

Ironically (serendipitiosly?) just as we are talking about Iron Rain... 

Where do these people actually see evidence for droplets and/or rain, in contrast to condensation on the/a surface? *grrrr*
They actually do mention rain in at least one of their papers: https://www.eso.org/public/archives/releases/sciencepapers/eso2005/eso2005a.pdf (last sentence on page 6). But they only mention it as a possibility and don't really give evidence that it actually happens.

I though about this some more, and I think that you'll get only rain when the atmosphere cools faster than the surface, otherwise the vapor will condense on the surface and doesn't form droplets. Molecules - like water or methane - can effectively cool via radiation, so the atmospheres on Earth, Titan, and other cool bodies (where molecules are stable) form clouds. But AFAIK mono-atomic metal vapors don't radiate efficiently, compared to liquids of the same material. Thus the surface should cool faster than the atmosphere and all the material condenses there without forming clouds.

Edited by AHHans
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JoeSchmuckatelli

JoeSchmuckatelli

Posted
Posted (edited)
1 hour ago, AHHans said:

Where do these people actually see evidence for droplets and/or rain, in contrast to condensation on the/a surface? *grrrr*
They actually do mention rain in at least one of their papers: https://www.nature.com/articles/s41586-020-2107-1.epdf (page 4, last sentence before "Online content" sub-title). But they only mention it as a possibility and don't really give evidence that it actually happens.

I though about this some more, and I think that you'll get only rain when the atmosphere cools faster than the surface, otherwise the vapor will condense on the surface and doesn't form droplets. Molecules - like water or methane - can effectively cool via radiation, so the atmospheres on Earth, Titan, and other cool bodies (where molecules are stable) form clouds. But AFAIK mono-atomic metal vapors don't radiate efficiently, compared to liquids of the same material. Thus the surface should cool faster than the atmosphere and all the material condenses there without forming clouds.

I'm no scientist - and while I find condensation as you suggest, plausible...  my reading of the article suggests that it's a gas giant and the day side atomized iron rains on the night side...

Thus, with no surface to condense on... It likely follows a similar pattern to rain here where the water molecules first bind to some other dust particle before gathering other water molecules sufficient to overcome the atmospheric uplift enabling it to fall. 

Edited by JoeSchmuckatelli
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AHHans

AHHans

Posted
Posted
4 hours ago, JoeSchmuckatelli said:

I'm no scientist - and while I find condensation as you suggest, plausible...  my reading of the article suggests that it's a gas giant and the day side atomized iron rains on the night side...

Hmmm... Well, it's no gas giant like we have in our solar system: it's *bleep*ing hot and close to its star. Because of that I thought it is something like mercury in big, i.e. with essentially no atmosphere. But now that you mention it: its also really heavy (a rocky planet the size of Jupiter!), so it's incredible gravity may also prevent some atmosphere from being blown away by the star.

Hmmmm....

But if it had an atmosphere with molecules in it, then they should have seen these molecules in the spectroscopy that they did. But I haven't seen anything like that mentioned in the paper. (I haven't read it completely, though.) I kind of would have expected that though...

So I'll revise my opinion from "no way that there is iron rain on that planet" to "I think it's rather unlikely that there is iron rain on that planet". :cool:

P.S. When writing papers to be published in Nature or Science it is somewhat usual to mention something that the data doesn't really warrant but sound awesome. In the paper itself they mention rain exactly once as: "Hence, it could literally rain iron on the nightside of WASP-76b". Which is not the same as "we have evidence that it rains iron [...]".

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