Here are some fascinating (for some people anyway) photos and videos of interesting condensation clouds that form around jets as they fly at or near the speed of sound, (often called "going through the sound barrier" or "accelerating past the speed of sound"). Under the right conditions, and even at lower speeds, they sometimes cause a vapor cone effect.
Understand that these Prandtl-Glauert condensation clouds can also occur at lower speeds, and are not really a visible manifestation of some kind of a sound barrier being broken.
The pics not mine. They were passed around via email and I've put together quite a bit of info I've found or been sent about each. Enjoy! -- jeff
Condensation cloud as an F/A-18 Hornet flys at or near the speed of sound.
Photo by John Gay.
Learn about what is causing this effect:
Explanation of the Physics of this Effect: Professor Mark Cramer of Engineering Science and Mechanics at Virginia Polytechnic Institute has written discussions of this effect at:
Note that Mark says: "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."
Wikipedia, the free encyclopia, has a number of very useful and enlightening entries to explore.
By the way, if you are coming here to
find out what the 'speed of sound' is, don't email me.
Georgia State Univ: Speed of Sound in Air,
All about this photo:
Awesome - Wanna see a sonic boom?
This photo has been around (and asked about) enough that it
is listed in these US Navy FAQs as
The shot seen 'round the world,
with a higher resolution copy
and the following description. (Thanks to Michael Manlin for
sending me this info.)
Navy Lt. Ron Candiloro's F/A-18 Hornet creates a shock wave as he breaks the sound barrier July 7. The shock wave is visible as a large cloud of condensation formed by the cooling of the air. A smaller shock wave can be seen forming on top of the canopy. It is possible for a skilled pilot to work the plane's throttle to move the shock wave forward or aft. Candiloro is assigned to Fighter Squadron 151, currently deployed with the USS Constellation battle group. (U.S. Navy photo by Ensign John Gay)
The explanation that came in an email with this photo and video:
Other photos of the same effect:
7/2007 New! iStockPhoto contributors have captured this effect too with a variety of aircraft. Here is a lightbox/gallery with some of their shots. These are high-quality photos, and are for sale (by them, not me). And links to some individual photos... F-22A Raptor's: 3490739, 3490794, 3144449, 3449195, 3158085, 2255168, 3351670, F-18's: 474872, 1011883, 1020731, 3293746, F-15's: 3449353, 3449365, 3486093, F-16's: 1004304, 1832402, 1065161, 1114649, F-111's: 1827647 (if you join istockphoto, please do me a favor and list me 'jwilkinson' as referrer. thx!)
ChamorroBible.org has quite a lot of great
photos in their Prandtl-Glauert Condensation Clouds Collections:
Be sure to check the
US Navy Eye on the Fleet Photo Gallery
for tons of great photos. Here are a few of the vapor effect.
F/A-18 vapor cone at Moffett airshow 8/11/01
Doug Wade also has some great photos from the Moffett Air Expo including some with the vapor cones. He says "the technical quality isn't as good as Nick Chinn's but you can see how sharp the thing became at one moment."
Here's a nice photo by Gregg Stansbery with condensation effect as a B1-B makes a high-speed pass very near the sound barrier at the Pensacola Beach airshow. From the 127th BS/184th BW, Kansas ANG. (also here)
F-14 Tomcat flyby
See Mark Cramer's explanations of the "Sonic Boom, Sound Barrier, and Condensation Clouds" above to understand why the vapor cloud forms.
On OK3 you'll find several different videos of aircraft breaking the sound barrier or causing the vapor cone effect as well as interesting photos and info on carrier landings.
Similar videos of this effect:
Download spots for this video:
Unfortunately the overwhelming popularity of this video was causing me to wildly surpass the transfer limits I'm allowed on my webhosting account. This file alone caused 25GB of transfer in March 2001. 60,716 requests!. So, much as I hate to, I had to remove the actual video file. Luckily it's available many other places, so see my list of download spots above. ~jeff
You can find a copy of the file on the other sites listed here. Please DO NOT email me requesting the video file.
Ken Payne wrote and says that the video was taken during a Family Day cruise event on the USS Enterprise CVN-65 July 29th 2000. He was standing in about the same place as the photographer and he recognizes someone in the video, though he doesn't know who took it. There are more pics from that day on his site.
Alternately, Stacey Sutcliffe says: "Ken Payne is mistaken (the Navy does this for all family day cruises and Tiger cruises, I'm sure they did have one just not this one). This video took place on the USS Theodore Roosevelt CVN-71 in 1986 for the tiger cruise. Here is the link to the Roseys web site. (webarchive copy) This cruise actually took place in 1987 of the coast of South Carolina on our way home from a Carrier Qual. We stopped in Ft. Lauderdale FL and picked up relatives for the ride back to Norfolk, VA. How do I know this is correct? I was there attached to AIMD SeaOpDet Airframes IM-2 Div. My Parent Squadron was VF-41 the Black Aces. This happens to be VF-41's CO, Commander Shuman the a/c was AJ101." (no, I'm not definitively sure which of them is correct. oh well, ~jeff)
Alex Tolmachoff writes: I just viewed the video you have of the Tomcat in transonic flight next to a carrier. I don't know the exact source or story of the film clip, but I can tell you where I first saw it and why. I am a U.S. Navy pilot flying C-130's in New Orleans and I am the Aviation Safety Officer (ASO) in my squadron. ASO's are sent to an intensive course of study in Monterey CA which includes a course in aerodynamics. We were shown this clip during a discussion of transonic and supersonic airflow and how it affects airplanes. If you watch closely, you will notice that the nose of the Tomcat dips down as it passes the carrier deck. The shock wave forming on the wing changes the center of pressure and thus the aerodynamic center of the airfoil. This creates a pitch down moment until the entire airfoil is supersonic.
B-2 Spirit Stealth Bomber. Photo by Bobbi Garcia.
Posted here with permission of the AFFTC.
Edwards photographer awarded first place in photo contest: Photo by Bobbi Garcia, a civilian aerial photographer who works for Rohmann Services in support of the Air Force Flight Test Center (AFFTC) at Edwards Air Force Base, took this photo of a B-2 completing a mission over the Pacific Ocean, which appeared in the December 30, 2002 Aviation Week and Space Technology, to win the magazine's photo contest. (Thanks to Mark W. for this info)
This photo is probably the same effect as the others shown above, even though, according to various sources, the B-2's max speed is high-subsonic and so it can't break the speed of sound. See Mark Cramer's explanations of the "Sonic Boom, Sound Barrier, and Condensation Clouds" above.
Thanks to the photographer, I now have a nice quality, high-resolution copy of this (2250 pixels wide). In case it becomes popular and overwhelms my bandwidth limits here, I've posted the larger copies in a webshots album.
From the Photographer, Bobbi Garcia:
On a personal note: I originally posted this page just to share some interesting photo and video files that had gone around via email with some friends and family. I hardly even linked it in from my site. Eventually the search engines got to it. As people sent me additional information I added it and the search engines ranked it higher and higher for this topic. It has gotten a tremendous amount of attention and traffic and I've gotten more fascinating email as a result than from anything else I've ever done on the web. Thanks for all your notes. -- jeff wilkinson
Just to be clear: I take no credit at all for these photos or video and claim no ownership or control. They were passed around via email. I just collected information about them. If you are the author of one and have issues with this, please email me.