Wilk4: Breaking the Sound Barrier (and Vapor Cones around Jets)

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

F/A-18 breaking the sound barrier (10k)
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: I highly recommend you spend some time exploring his site for its information and also for the many photos and examples of shock waves and other similar condensation clouds forming around jets in flight.

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."

Learning More:

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. Try Wikipedia, Georgia State Univ: Speed of Sound in Air, or Aerospaceweb or Google.
For who first broke the sound barrier, try Wikipedia: Sound barrier, Aerospaceweb, this personal account or Google.

All about this photo:

Awesome - Wanna see a sonic boom?
by Bruce Stephen Holms

Ensign John Gay could see the fighter plane drop from the sky heading toward the port side of the aircraft carrier Constellation. At 1,000 feet, the pilot drops the F/A-18C Hornet to increase his speed to 750 mph, vapor flickering off the curved surfaces of the plane.

In the precise moment a cloud in the shape of a farm-fresh egg forms around the Hornet 200 yards from the carrier, its engines rippling the Pacific Ocean just 75 feet below, Gay hears an explosion and snaps his camera shutter once. "I clicked the same time I heard the boom, and I knew I had it," Gay said.

What he had was a technically meticulous depiction of the sound barrier being broken July 7, 1999, somewhere on the Pacific between Hawaii and Japan. Sports Illustrated, Brills Content and Life ran the photo. The photo recently took first prize in the science and technology division in the World Press Photo 2000 contest, which drew more than 42,000 entries worldwide. "All of a sudden, in the last few days, I've been getting calls from everywhere about it again. It's kind of neat," he said, in a telephone interview from his station in Virginia Beach, VA.

A naval veteran of 12 years, Gay, 38, manages a crew of eight assigned to take intelligence photographs from the high-tech belly of an F-14 Tomcat, he fastest fighter in the U.S. Navy. In July, Gay had been part of a Joint Task Force Exercise as the Constellation made its way to Japan.

Gay selected his Nikon 90 S, one of the five 35 mm cameras he owns. He set his 80-300 mm zoom lens on 300 mm, set his shutter speed at 1/1000 of second with an aperture setting of F5.6. "I put it on full manual, focus and exposure," Gay said. "I tell young photographers who are into automatic everything, you aren't going to get that shot on auto. The plane is too fast. The camera can't keep up." "At sea level a plane must exceed 741 mph to break the sound barrier, or the speed at which sound travels.

The change in pressure as the plane outruns all of the pressure and sound waves in front of it is heard on the ground as an explosion or sonic boom. The pressure change condenses the water in the air as the jet passes these waves. Altitude, wind speed, humidity, the shape and trajectory of the plane - all of these affect the breaking of this barrier. The slightest drag or atmospheric pull on the plane shatters the vapor oval like fireworks as the plane passes through," he said.

"Everything on July 7 was perfect," he said. "You see this vapor flicker around the plane that gets bigger and bigger. You get this loud boom, and it's instantaneous. The vapor cloud is there, and then it's not there. It's the coolest thing you have ever seen."

(This article was sent to me by Carter Slusher)

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.)

An F/A-18 Hornet assigned to Strike Fighter Squadron One Five One (VFA-151) breaks the sound barrier in the skies over the Pacific Ocean, July 7, 1999. VFA-151 is currently deployed with USS Constellation (CV 64). U.S. Navy photo by Ensign John Gay. July 7, 1999.

Ensign John Gay, photo officer for Fighter Squadron Two (VF 2), shot this image from the 0-10 level weather deck (the uppermost deck on the island) of USS Constellation (CV 64). It was shot with a Nikon N-90s with a Nikon 70-300 ED zoom lens, using Kodacolor 200 negative film. The camera was set for manual exposure of F/5.6 at 1/1000 sec. The image was acquired with a single shot, panned from left to right, prefocused at approximately 200-300 yards off the port side of the ship, where the aircraft flew by.

Find this photo at as #990707-N-6483G-001 in the US Navy Eye on the Fleet Photo Gallery, where they note that it was taken off the coast of Pusan, South Korea. (high resolution copy)

DefenseLink: The Sight of Sound also posted the photo and a higher resolution copy (958k) with the following description.

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:
This is extra ordinary photography, once in a life time photo. Hope you enjoy. Every so often, just the right combination of conditions and events occur to create an unbelievable event-in this case an F-18 passing through the sound barrier. Not only were the water vapor, density and temperature just right, but there just happened to be a camera in the vicinity to capture the moment. The F-18 is actually in transonic flight, with normal shock waves emanating from behind the canopy and across the wings and fuselage. The condition will last for only an instant, and once supersonic flow exists completely around the aircraft, sharp-angled sonic cones replace the normal shock waves. The odds of getting a shot like this are staggering.

Other photos of the same effect:

7/2007 New! click to see more on iStockPhoto 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... click to see more on iStockPhoto 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: 1, 2, 3, 4, 5.
Each collection has photos, details, credits, links to high-res photo copies and lots of links to more.

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. 1445, 1386, 2827, 4598, 7030, 8767, 11676, 14863, 17909, 19053, 23018, 23503, 26590, 26610, 27228. 27251, 27327, 28334, 34239, 37555, 37558, 39127, 39129, 39964, 39972, 40228, 40674.
All Hands Gallery: 1066.

You can see an F-4 creating the vapor cone as it breaks the sound barrier at OK3 or Physics Movies.

F/A-18 vapor cone at Moffett airshow 8/11/01
Nick Chinn says: I was at the Moffett Air Expo on Saturday, August 11, 2001 and they had a high speed F/A-18 flyby. He approached the speed of sound but there was no sonic boom so he did not break it (this is a mostly residential area). The air was certainly crackling though! A vapor cone still formed and I caught a couple pictures of it. (pics are toward the bottom) The shots were taken with a Canon D30 digital SLR and a 100-400mm zoom.

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."

Yung Chen from Canada sent in a note that he caught some good pics of this effect at the 2001 London Air show. See them under Photo Album: F14-B

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)

Related Links:

Videos of Jets causing this kind of vapor cloud    (#)

F-14 Tomcat flyby
Screenshot from the video
(screenshot from the video, NOT the video itself)

Screenshot from the video
(screenshot from the video, NOT the video itself)

This video came without any info. It is an F-14 Tomcat. If you know any more information about this video or its source, please let me know. -- jeff

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... same effect?    (#)

B-2 bomber SUB-sonic
B-2 Spirit Stealth Bomber. Photo by Bobbi Garcia.
Posted here with permission of the AFFTC.
(higher-resolution version)

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:
As for how I got the shot. I was in a chase F-16 being flown by Maj "Bernie" Cassidy. Between test points we would try to capture the condensation on still film. The camera I was using was a Hasselblad with a power winder (equates to about 1 frame per second) and the vapors only happen briefly and sporadically. As you can imagine, there was a little "spaz action" going on, trying not to take any unnecessary photos that would cause the power winder to be busy when I needed to be actually shooting.

We were fairly low in altitude when the shot was taken, and heading home from the mission.

There is enough moisture over the ocean to actually cause that phenomon to happen at various speeds, not just supersonic. That is why people on the navy carriers can get that shot more often than most land-based aircraft photographers.

Related Links:

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.