When jets are flying why does a bubble or circle of air(?) flash around it?

When I was watching the jets fly @ the air and sea show. I noticed sometimes a circle of air would flash around the aircraft.. Does anyone know why that happens/ what it is?

When jets are flying why does a bubble or circle of air(?) flash around it?
Sounds like you are describing the Prandtl-Glauert singularity as the jet is in the transonic regions of flight.
Reply:Contrails or vapour trails are condensation trails and artificial cirrus clouds made by the exhaust of aircraft engines or wingtip vortices which precipitate a stream of tiny ice crystals in moist, frigid upper air.





ps:or if you`re referring to breaking the sound barrier. You see a puff of smoke (sortah) in the shape of a cone starting from the tip of the aircraft to its rear. But if she was close enough to see that then there must not have been other building and stuff around. cause breaking the sound barrier at low altitude would cause some discomfort and possibly damage to windows if you done to close. This is why I think its Contrails of Vapor trails
Reply:Quite possibly they are getting close to the speed of sound. However I seen this just yesterday and the F-16 I seen was no where near 760 mph. It's actually just the air passing over the wings of the aircraft moving at an incredible rate of speed. At air shows the aircraft hardly ever break the sound barrier so I doubt it was that....but possible. And when it's a big circle around the midsection of the aircraft that's when they are about to break the sound barrier. Pretty cool isnt it!
Reply:they are getting ready to break the sound barrier.

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