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What happens when a supersonic airplane flies through a cloud? Will it punch a hole or is it more like a bullet through water (= hole closes immediately after the aircraft has passed)?

Is there some special effect because of the supersonic speed? Or maybe the question should be: Does the airflow around an airplane change when the sound barrier is broken?

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It comes out the other side. :: rimshot:: –  Colin K Feb 27 '12 at 23:49

2 Answers 2

up vote 4 down vote accepted

It creates shock waves, which under the right conditions like a supersonic rocket did in this picture, causes concentric cloud rings. Clouds are essentially just volumes where the humidity, temperature, and pressure are such that the air is locally supersatured with water. The craft passing through the cloud will send out waves that disturb the pressure, changing the saturation and causing visible ripples.

enter image description here

EDIT: For a diagram of what is happening here, see this image.

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Very interesting answer. Is the cloud deformed that gets pierced by the rocket? –  Aaron Digulla Feb 28 '12 at 14:43
    
It doesn't make sense that that rocket was supersonic (one wouldn't see shocks so far in front, nor so numerous, I would think; also the waves are concentric round rings, they do not look like not conical or curved bow shocks). I think it is more likely that the rocket was going at a very high subsonic Mach number when that photo was taken. It's hard to tell the scale but if ring 1 was 50m in front and ring 11 was 120m in front, that would suggest that ring 11 was emitted about a quarter of a second before ring 1 was...? –  Daniel Chisholm Feb 28 '12 at 15:21
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An Atlas V rocket certainly goes supersonic. If you go to the linked page, you can see that the shocks map to the discontinuities in the rocket surface quite nicely. Also, the shocks are not in front - it's hard to tell but the shocks form a cone behind the rocket. Again, check the linked page for a diagram. –  Mark Beadles Feb 28 '12 at 15:28
    
@AaronDigulla It's a cloud layer it is going through...I wouldn't say it's deformed as such; really the effect is sort of like ripples on a pond when you throw a pebble in. –  Mark Beadles Feb 28 '12 at 15:32

Couldn't find a cloud image but this is interesting

edit: Apparently this is due to the drop in pressure immediately behind the shock wave of a supersonic aircraft. (Like a moving cloud chamber?)

enter image description here

photo is by US navy and therefore public domain.

There are a whole set of similar images here

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Actually that's not an accurate description of what's happening in the picture. You don't make water vapor condense by compression, and the shock wave starts at the front of the plane not the middle. I believe what is depicted in this picture is actually a Prandtl-Meyer expansion fan. –  user1631 Feb 27 '12 at 23:06
    
It's a "Prandtl-Glauert cloud" from the P-G 'singularity'. –  Mark Beadles Feb 28 '12 at 1:24
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Another interesting thing that this photo shows is that condensation is very quick to form (fractions of a second, at most), AND it is also very quick to dissipate. So to answer the OP's question, even if a jet momentarily punched a visible hole through a cloud, it is quite possible that that hole would nearly instantly close up again once the jet has passed. –  Daniel Chisholm Feb 28 '12 at 15:23

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