Finally a good sonic boom photo. Upvote this so it gets into image results for "sonic boom".
this post was submitted on 14 Sep 2023
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I wish these images of the ring-clouds and shockwaves would stop being posted as the event that denotes the transition of the aircraft to supersonic flight.
No. This does not indicate the sound barrier was just broken.
Shockwaves begin to form in subsonic flight when parts of the aircraft may experience transonic speeds. Even airliners can have transonic flow, the MD 80 was known for having a visible shockwave on the wing you could see if the sun hit it just right.
Shockwaves exist and grow from subsonic, to transonic, to supersonic flight as different parts of the aircraft experience different airflow.
At no point is there a shockwave that appears signifying the transition of the aircraft as a whole to supersonic flight.
No no no. The plane had to push really hard until it bursts through the sound barrier like it's going through a balloon! That's why you hear it go BOOM. it's the big sound balloon popping!
/s
why is this visible?
So as a pilot and a hobbyist photographer I wasn't able to come up with a definitive answer from google. Virtually all results end up on schlieren photography which is something I've been aware of, but only in controlled settings. I do think it might be the answer here though. The ELI5 answer is that it takes super fast shutter speeds which require a lot of light. This photo is conveniently lit by the sun behind the F-18 which means it is basically a pseudo schlieren setup. Super bright source behind the image but blocked just enough to not bloom it out allowed for the super fast shockwave to be captured. If anyone knows more please feel free to chime in, I would love to learn more on this.
What we see is light being refracted in "weird" ways. It's similar to the way light above a very hot surface, like asphalt on a hot sunny day, appears to be warped.
Everything has a refractive index, meaning a number that determines how much light is warped. Air is usually very evenly distributed, so you don't see much (or any) warping. But the airplane moves so fast that it pushes the air in front of it to the side, which means around the airplane the air is denser. The refractive index of air changes with density. This makes the light appear so warped :)
Fun fact, the sonic boom also comes from the air being pushed to the side. Behind the airplane there is a pocket without air (or with very little). The higher density around the airplane is not stable, gases want to be evenly distributed. This makes the air crash violently into itself as it fills the pocket, which produces the sound! This also explains why you hear the sonic boom everywhere along the path of the airplane, and not just where it breaks the sound barrier.
But then that means what we see has nothing to do with breaking the speed of sound. So is the only relation between the distortion and breaking the sound barrier the fact that one needs to be quite fast for both?
Yes, in the sense that you already get a weaker version of this effect below the sound barrier. You don't need to break it to see them.
Why is this nsfw?
I guess this is too sexy for some people
The entire @[email protected] community is
It’s so they don’t get ad money. Oh wait that was the old place
Is it? I don't see the NSFW tag!
It does look kinda hot.
This effect happens continuously as long as the plane is traveling faster than the speed of sound. Sonic booms are not a one time thing that only happens when you "break the sound barrier". The concept of it being a barrier at all comes from before we could go that fast and it was believed to be impossible due to infinitely increasing drag as you approach it.