What is Digg?80 Comments
- lenwood, on 10/12/2007, -1/+55These are awesome. Digg. For anyone interested, here's what's happening:
What you see in these pictures is water vapor condensing in the shock waves around the plane. Translated: there is very high pressure at the tip of the plane, and also behind the plane, but as the plane speeds through the sound barrier it flies through a low pressure zone. The puff that you see is the moisture in the air condensing in this region of low pressure. This puff happens at the exact same instant that you would hear the sonic boom. So because of the moisture in the air you can actually "see" the shock wave.
There are couple of things that are fascinating about these pictures. First, they were taken at exactly the right instant, this puff is visible for less than a second. Once the jet accelerates through the low pressure zone, the pressure equalizes and the water evaporates back into the air. And second, if the air were dry, you wouldn't see anything other than a plane speeding up. - Teratogen, on 10/12/2007, -0/+14I have a video of an F-14 going through the speed of sound at about 100 yards away. You can find it here:
http://www.users.qwest.net/~intertwingled/sonic.mpg - tpodr, on 10/12/2007, -0/+11Example of a Prandtl-Glauert cloud.
One during the launch of Apollo 11, http://www.nasa.gov/multimedia/imagegallery/image_feature_359a.html
More information
http://lofi.forum.physorg.com/Discovery-created-a-Prandtl-Glauert-cloud_2520.html
http://linkfilter.net/?id=90041 - bondg, on 10/12/2007, -0/+6Sorry lenwood, this is not at all how sonic booms occur. There is no "exact same instant that you would hear the sonic boom."
A sonic boom is an ongoing phenomenon. When an aircraft (or rocket or meteor or really fast snot-rocket) is traveling faster than sound, there is a cone-shaped zone whose apex is at the the leading edge of said aircraft and which extends back and away from this apex. As the craft passes by you, you are enveloped in this cone-shaped zone and you hear the sonic boom.
If you and I and a hundred other folks were spaced at say, 10 yard intervals, lined up along the ground, following the path of the ultrasonic craft, we would each hear the boom, each in our own turn as this "cone zone" passed over us (assuming the craft isn't so far away that the boom dissipates before it reaches us). - Big_Zack, on 10/12/2007, -0/+4Sorry, A Prandtl-Glauert cloud (vapor or condensation cloud) is not a sonic boom. There are tons of these types of image in the Internet making the same claim, but it's just not true. I have seen many vapor clouds like this on jets during my stay at Naval Air Station Oceana (VA), and there are VERY strict regulations about not going supersonic anywhere near the base (anywhere other than out at sea). More info here: http://www.fluidmech.net/tutorials/sonic/prandtl-glauert-clouds.htm
Here is another video with audio... take note - no boom: http://home.pacbell.net/ok3/f-18flyby.mpg
Regardless, still a cool photo. Digg. - canyonblue, on 10/12/2007, -0/+3tons of more examples:
http://ChamorroBible.org/gpw/gpw-20040817.htm
http://ChamorroBible.org/gpw/gpw-20040818.htm
http://ChamorroBible.org/gpw/gpw-20041216.htm
http://ChamorroBible.org/gpw/gpw-20041217.htm - Guspaz, on 10/12/2007, -0/+2Cool. but why is it on a "paranormal" site :P
- rusty_g, on 10/12/2007, -1/+3not really rare, or even unexplained...
- vroom101, on 10/12/2007, -0/+2@codyph55
According to the photo credit for pic #11 (the original NASA image) at http://ChamorroBible.org/gpw/gpw-20040817.htm it is from a frame grab. How did you know that!?!?
@bondg
I'm no expert in this stuff. That said, it looks like you're right about the hearing continuous sonic booms (popular topic these days too):
http://fluidmech.net/tutorials/sonic/sonicboom.htm (English)
http://curiosoperoinutil.blogspot.com/2005/12/la-barrera-del-sonido.html (Español)
http://curiosoperoinutil.blogspot.com/2005/12/la-barrera-del-sonido-ii.html (Español)
http://www.palestinemonitor.org/nueva_web/articles/features/demons_gaza_sky.htm (English)
http://abcnews.go.com/WNT/story?id=1453692 (English)
While the fighter jet/bomber photos aren't rare today--can't really say that about images of space vehicles like the shuttle or a rocket--I'm guessing that what causes the condensation cloud, the Prandtl-Glauert Singularity, explained in understandable layman's language is fairly recent. As already noted by @big_zack, see http://fluidmech.net/tutorials/sonic/prandtl-glauert-clouds.htm for an engaging explanation.
Now if only my calculator would create a minature Prandtl-Glauert cloud when I type in 1/0--one divided by zero--instead or "error"!
+Digg for the post and most definitely for the comments! - Kevin108, on 10/12/2007, -0/+2Lt. Col. William Guile could not be reached for comment.
- GekigangerV, on 10/12/2007, -0/+1And another FYI, at this point in the mission, the shuttle isn't going "that fast." In orbit, the orbiter is traveling at 17,500 mph at an altitude of 200 nm. It only has to slow down a few hundred mph to deorbite and begin reentry.
- ChrisGranger, on 10/12/2007, -0/+1Nifty photo, but ridiculous that it appears on a site for unexplained mysteries. Not news, and sonic booms have been imaged and well understood for ages.
- GekigangerV, on 10/12/2007, -0/+1I doubt that you guys would care, but this photo is upside down. At this point in the mission, approximately 1 minute in, the shuttle has already completed it's Positive Roll Maneuver and is in a heads down wing level position. This is done to take structural loading off of the orbiter and place it on the external tank as well as to give a fluid shift in the ET for liquid oxygen and liquid hydrogen to a position closer to the center of gravity of the shuttle.
- tburke261, on 10/12/2007, -1/+2It would be great if digg could have a poll system, so users could vote on things like this, with options such as real, and photoshopped. Anyone else agree with me?
- codyph55, on 10/12/2007, -0/+1that was sweet... but it looks more like a frame grab from a video then a still photograph
- JDOG, on 10/12/2007, -0/+1Nice pic
+digg.
Why does everyone require something earthshaking to be dugg these days? I was perfectly content to look at the picture and go "hey, that looks cool." nuff said. - DF25863, on 10/12/2007, -0/+0Like others have said, this is not a Sonic Boom. Here is a picture of a Boeing 777 with the same effect over LAX. And I can assure you that it is not supersonic ;)
http://www.airliners.net/open.file/981791/M/ - deadkenny, on 10/12/2007, -0/+0Title is wrong. It's NOT a sonic boom.
It's the same with all those "sonic boom" fighter jet photos. They are NOT sonic booms!! When will people get this right!! - lerch, on 10/12/2007, -0/+0lol, awsome pics/vids everyone
+digg - jerbaker, on 10/12/2007, -0/+0People will not get it right ever. The reasons are the same reasons people believe that the Earth is 5,000 years old, or that there really are ghosts, and that shows like the X-Files are actually informing us about things that go on in "super secret" government operations.
- xofc, on 10/12/2007, -0/+0There's a difference between the condensation clouds that form over the low pressure area of a wing and the condensation clouds that form in the wake of a shock wave. They form for the same reason, though. When air suddenly passes from ambient pressure to very low pressure, it can hold less moisture both because of its lower pressure and because of its reduced temperature (the ideal gas law states that P*V is directly proportional to T, temperature). Some of the water vapor then condenses to form a cloud and will almost immediately return to a vapor state when returned to ambient temperature and pressure, which it will once the disturbance passes.
In the 747 picture, the pronounced low pressure area is caused by the wing with the flaps extended. Viewed from the sides, the clouds would be curved, as you'd expect with normal, subsonic aerodynamics. In the Space Shuttle picture, the low pressure area is caused by the supersonic shock wave, which is fairly straight-edged cone. In the picture, the cone looks to be at a fairly wide angle, which means the shuttle is only slightly above the speed of sound:
"For supersonic and hypersonic flows, small disturbances are transmitted downstream within a cone. The trigonometric sine of the cone angle b is equal to the inverse of the Mach number M and the angle is therefore called the Mach angle.
sin(b) = 1 / M" (http://www.grc.nasa.gov/WWW/K-12/airplane/mach.html)
The faster the aircraft flies, the more acute the angle of the cone.
http://www.tpub.com/weather3/6a-26.htm - vroom101, on 10/12/2007, -0/+0@DF25863
"Like others have said, this is not a Sonic Boom. Here is a picture of a Boeing 777 with the same effect over LAX. And I can assure you that it is not supersonic ;)
http://www.airliners.net/open.file/981791/M/"
Now that 777 picture is awesome. I've seen condensation like that in photos of fighter jets, but not on a commercial jet. I have a question though whether the effect is caused by the Prandtl-Glauert Singularity. Here's why: (a) Assuming the 777 is qualified to fly at transonic speeds (speeds right around Mach 1), would it do so with the wheels down? And (b) see the section "Lift-Induced Condensation" at http://www.fluidmech.net/tutorials/sonic/prandtl-glauert-clouds.htm . Given the popularity of this digg story, maybe there's someone out there that help us out with the 777 picture.
@CLIFFosakaJAPAN
So far, there are only three known public images of space vehicles with a Prandtl-Glauert vapor/condensation cloud: (1) The photo in the digg story ("Rare photo of Space Shuttle Sonic Boom" by CLIFFosakaJAPAN) of STS-106, Space Shuttle Atlantis (see the photo credit for image #11 at http://ChamorroBible.org/gpw/gpw-20040817.htm ). (2) The Saturn V rocket in the Apollo 11 launch. Have a look at the comment by tpodr at 12:58 AM 1/01/06, it's the second comment from the top. (3) STS-114, Space Shuttle Discovery http://msnbcmedia.msn.com/j/msnbc/Components/Photos/050805/050805_shuttle_hmed_1130.hmedium.jpg (via http://www.msnbc.msn.com/id/8790614, "Cosmic Log: Discovery's clouds of glory," 5 August 2005) and the center image at http://ChamorroBible.org/gpw/gpw-The-Spectacular-Clouds-of-the-Transonic-Flight-Regime.htm (it's also image #13 at http://ChamorroBible.org/gpw/gpw-20040817.htm ). It can also be seen in the STS-114 launch video as pointed out by in the comment by tpodr at 12:58 AM 1/01/06.
Maybe a search of the NASA Image eXchange (NIX) at http://nix.nasa.gov and other NASA image/video archives will reveal many more images of _space vehicles_ with the Prandtl-Glauert cloud. Until that happens though, rare it is. Hopefully at the next shuttle launch it'll be a clear day, lots and lots of high-resolution cameras focused on the shuttle and the atmospheric conditions (not sure what those would be!) are primed for a Prandtl-Glauert cloud. Then as the orbiter accelerates through the transonic regime the Prandtl-Glauert Singularity kicks in -- Presto! a Prandtl-Glauert cloud appears and perhaps stays around long enough for it to be photographed. - messiah, on 10/12/2007, -0/+0Ok DEADKENNY....if its not a sonic boom then explain away...oh and try to explain away xfoc's comment above while your at it. This just reinforces my earlier comment......morons...
- dirtyfratboy, on 10/12/2007, -0/+0CONGRATS ON BEING TOP STORY OF THIS YEAR!!!!!
- switchman401, on 10/12/2007, -0/+0Nice!
- Jessimo, on 10/12/2007, -0/+0nice. i've never seen any pictures like this, and all the other examples in the comments are great. i would digg more than once, but can't
- way2slo, on 10/12/2007, -0/+0I could have sworn that the Shuttle only went supersonic at a low enough altitude to cause a sonic boom during re-entry. I thought that by the time the Shuttle does have enough speed to cause one during lift-off that it was too high and there was not enough air.
- lenwood, on 10/12/2007, -0/+0Thanks to all for catching my error, this isn't a sonic boom. That's what I get for commenting before I had my coffee. FWIW I think xofc did a better job of addressing this than anyone.
- deadkenny, on 10/12/2007, -0/+0@messiah ...
http://fluidmech.net/tutorials/sonic/prandtl-glauert-clouds.htm
Though the clouds can occur at near to supersonic speeds, often just under or over, they are not themselves a representation of the sonic waves or "boom".
quote...
"A common error is to state that the cloud "visualizes shock waves". As indicated above, the front of the cloud has nothing to do with the shock wave."
and finally...
"Finally, it should be clear that Prandtl-Glauert condensation has nothing to do with "breaking the sound barrier" and is not a Star Trek-like "burst" through Mach one. An aircraft can generate a Prandtl-Glauert condensation cloud without ever exceeding the speed of sound."
So there you go. - inactive, on 10/12/2007, -0/+0@JDOG
i agree woth u who cars if it aint rare or if its a frame grab its still a pic of a space shuttle breaking the sound barriar and making a vapor cloud even though u can see the vapor clouds on 747's and such and also dont need to be going that fast either it is still hard to take a pice of a space suttles making its own clouds
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http://www.frontlinetech.blogspot.com - LedZep95, on 10/12/2007, -0/+0sholy hit that's a good shot!
diggTotal ++; - messiah, on 10/12/2007, -0/+0JDOG, the reason people require something "earthshaking" in order to digg it these days is because many of them are Morons and they are insanley jealous that they themselves did not submit the stories. It is a cool pic, I dont give a crap if its not that rare...and I guarentee that 99% of the people who commented here do not see these pics on a regular basis.
Any for the morons who are complaining about it being on a paranormal site, if you took the time to actually look at the rest of the site the photo is in a seperate gallery for space pictures, and segregated from the paranormal stuff. Idiots.... - cyberghost232, on 10/12/2007, -0/+0OK. Who the hell took that photo?
- Teratogen, on 10/12/2007, -0/+0RMuffin, not sure now. I thought it was an F-14 going through the speed of sound just then. Now it could be an F-14 going slightly faster or slightly SLOWER than the speed of sound. It seems that Prandt-Glauert condensation clouds form at transonic speeds.
- CanuckPlumber, on 10/12/2007, -0/+0Dugg, regardless.
- Merlinhoot, on 10/12/2007, -0/+0That is a good site for Mysteries of the Unexplained
- flightvector, on 10/12/2007, -0/+0Yes, this is a common misconception, the instant of transition into the supersonic flight regime is coincident with the instant disappearance of the Prandtl-Glauert condensation clouds.
- trix911, on 10/12/2007, -0/+0awsome
- Zanza, on 10/12/2007, -0/+0WOAH! that's one cool picture!
- inactive, on 10/12/2007, -0/+0Google Image Search for "sonic boom" brings up a whole lot of images. Kinda negates the "rare" part of the dugg photo.
- stlcadet11, on 10/12/2007, -0/+0+digg just for the comments, this is what digg is about. not those annoying spammers
- rockyrobins, on 10/12/2007, -0/+0I just love that space shuttle. Thumbs up! A cool pic is a cool pic.
- jerbaker, on 10/12/2007, -0/+0Anyone who has been to an airshow has seen this phenomena repeatedly. It doesn't require supersonic flight to occur at all. All it requires is an area of low pressure. You can even see this happen on commercial planes at under 300 knots on a humid day as they adjust their flaps for landing. Although the pictures are nice, they may or may not be the result of breaking the sound barrier.
- sremick, on 10/12/2007, -0/+0Those aren't the only reasons the shuttle rolls during launch:
http://www.aerospaceweb.org/question/spacecraft/q0127a.shtml - vroom101, on 10/12/2007, -0/+0In the article "Lisa's Adventure", posted at http://quest.arc.nasa.gov/women/YWAC/sts106/lisa.html (via http://quest.arc.nasa.gov/women/YWAC/sts106/intro.html , "Lisa's Launch Adventure"), Lisa writes about NASA's STS-106 mission. Under "Day Two" she says:
"...At the Briefing, we are told what to expect if the launch goes. After ignition, the sound waves that will travel across the water the lies between the launch pad and the viewing site will create visible waves in the water. There will be lots of smoke and noise even though we are sitting several miles away. When the shuttle breaks the speed of sound, strange condensation forms around the shuttle. Two minutes after launch time, the SRB's drop off and you can usually see them fall back into the water. In only a few minutes, the shuttle will be out of sight."
Later on Lisa writes that everything "happens just as we had been told to expect." She doesn't say if she saw the condensation cloud around Space Shuttle Atlantis (STS-106). That the condensation cloud formed around the orbiter isn't in doubt because by now we've all seen the image taken from a video of the STS-106 launch.
About those "visible waves in the water". Here's a link to a video of an F-14 Tomcat breaking the sound barrier over the water. And the water is clearly being disturbed by the supersonic flyby: http://www.galleryoffluidmechanics.com/shocks/sfb.htm - NINJ4, on 10/12/2007, -0/+0Insanely cool, looks like a movie....
- Magistrate, on 10/12/2007, -0/+0++ :smiles: goes out to teratogen for the movie, and to lenwood for the awesome explanation, but no digg on the story. It's just a picture... hardly news-worthy.
- nebrfan, on 10/12/2007, -0/+0"wow, thats pretty cool. I didn't even know they went that fast, but now that I think of it it kinda makes sense that it would." - Umm.....you didn't think that an object had to travel faster than the speed of sound to enter orbit?
- inactive, on 10/12/2007, -0/+0Great pictures.. Exemples in comments are more impressive then picture in original story..
- vroom101, on 10/12/2007, -0/+0Prandtl-Glauert Condensation Cloud on a F/A-18F Super Hornet "Rhino" from VFA-122 "Flying Eagles" Flight Demonstration at Salinas 2005
http://www.sawmillcreek.org/showthread.php?p=269893 (post)
http://www.sawmillcreek.org/attachment.php?attachmentid=24437 (pic) -
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