what is the white cloud around a jet as it breaks the sound barrier?

Answer 1

You mean like this one?
http://www.ingeniumtr.com/tom/weblog/2003/08/supersonic-vapors.html .

It's actually caused by low pressure areas which form either above the wings at subsonic speeds during fast turning or lifting manuevers or at near supersonic (trans-sonic) speeds behind the aircraft. It's very common on military fighters where there is a lot of speed, weight and high G-force involved. It's more common in high humidity conditions but can also happen in low humidity enviroments if the jet is pulling hard enough.

Remember that when an aircraft is pushing the sound barrier, there is a lot of air pressure on the leading edges of the plane. Immediately behind this high pressure area will be a lower air pressure area, especially above the wings because the distance the air has to travel is greater (thus the molecules are separated farther apart) and the lower air pressure sucks the moisture out of the air momentarily.

The same thing happens on a much larger scale when a low-pressure storm moves in and the result is clouds and rain. Low pressure = clouds and high pressure = clear.

Jets can pull so much vacuum at speed that it's not uncommon for the entire plane to be covered in a fog just before it breaks the sound barrier.

Here's some more cool examples if you're interested:

http://www.niceemail.com/UFO1/f18vapor.jpg
http://www.richard-seaman.com/Aircraft/AirShows/Miramar2004/Highlights/BlueAngelPullingVapor.jpg
http://www.a-10.org/photos/Photos83586/oct07_33.jpg http://members.cruzio.com/~webcab/BartleyAaron/exercise5.html
http://jetpix.com/webfiles/f-16vapor.jpg

Answer 2

The jet isn't breaking the sound barrier, rather it is in transonic flight (very close to M1), however the air flow at certain places on the fuselage is going supersonic and there resultant loss in pressure cause the temperature to change and the vapor to condense out, hence the shock wave. Same thing as the "ectoplasm" on an F-16 pulling gs and an airliners landing in humid conditions -- the change in temp in the lower pressure area condenses the water vapor. If it's dry (low relative humidity) you won't see one.

Answer 3

It's actually a very rare phenomenon that happens at high humidity. Behind the shock wave is a low pressure area. When this low pressure area hits the air, the air instantly cools (think boyles law or such) and then the water vapor condesnse. When the next shock wave hits it, the air warms and evaproates the water.

Answer 4

Simple terms. Compressed air will not hold as much water vapour as uncompressed air.
The compressed air from the shock wave literally squeezes the water vapour out and it becomes visible for a fraction of a second.

Answer 5

i think you're refering to the video of an airforce jet flying next to an aircraft carrier and you can see a circular cloud form around it.

that cloud is water vapor being hit by the various physical forces surounding the jet, most specifically, it's the sonic wave catching up with the forward pressure caused by the jet and smashing the air/water in the air into a cloud vapor.

at least that's what my physics teacher told me.

Answer 6

That is the sound barrier, you cannot see it until you catch up with it.
the plane is accelerating through it>

Answer 7

means you have broken into Mr. Cleans air space. Shame on you