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Posted by s_ellebaut on 08-28-2003 9:38 AM
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I've seen a little movie where a jet breaks the soundbarrier, it creates a hughe cloud, what's the cause of this cloud forming? It's weird, you can even see the cloud bending when it's formed in front of the jet's nose just before the jet's inside the cloud. I've put the movie online: http://users.pandora.be/ellebaut/31tigersqn/soundbarrier.WMV
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Posted by KenV on 03-11-2005 10:02 AM
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This is a common occurance.
When flying transonic and low supersonic, the aircraft creates a powerful pressure wave (technically several waves, but one is predominant). It's like the bow wave a boat makes in the water. The area immediately behind the wave is a low presssure area. If the air is moist (high humidity) the moisture will condense in that low pressure area, which will appear as a "cloud". But notice that the "cloud" is moving with the aircraft which is moving at or above the speed of sound. That is impossible. What is happening is that the cloud is created in the low pressure area, the low pressure area moves forward, and the cloud dissappears. But a new cloud is instantly created in the new location of the low pressure area, and so on. So the cloud is not acutally moving with the aircraft, but instead a new cloud is created in each point in space as the aircraft moves through it.
Have you ever watched a space shuttle landing? You will see little cloud "streamers" come off the wing tips. The mechanism is completely different, but this is also a low pressure area where the moisture in the air condenses. The different mechanism causes the low pressure area to dissipate more slowly and so you see the cloud trail behind the shuttle a short distance.
Fighters doing heavy maneuvering in airshows also create transient clouds above their wings during high G maneuvers. A large area above the wing becomes a low pressure area and a "cloud" forms during the duration of the maneuver, usually only a second or less.
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Posted by vectorg on 12-11-2005 11:34 AM
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hi Ken,
A pilot friend told me once that when you see a vapor trail in the sky made by a passenger jet, the vapor comes from the jet engines. Is this always true? Can large vapor trails come from the wings or other parts of a high-flying plane? Thanks.
Gordon
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Posted by King_Wakka on 03-12-2006 3:48 AM
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basically the plane goes so fast that the air around the plane turns into a cone shape and starts to stretch to a point and then it breaks and now u have broken the soundbarrier
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