london-boy said:
The reasons for this "effect" are very complicated. Basically, when an object moves through air at a speed which is faster than the speed of sound, a "shock wave" is created (actually, it's a 3 dimensional cone whose vertex is at the front of the plane, and usually also on some other surfaces of the plane such as where the main wing meets the fuselage). Basically, a shock wave is a pressure disturbance (the surface of these cones) that is very thin (tens of molecules wide, or something like that). On one side (in front of the cone), the local pressure is high, but on the other side of the shock wave, the local pressure is much lower. When you hear a "sonic boom", it is the surface of this cone passing by your eardrums, which detect the pressure differential, which your brain interprets as sound. All the white smoke you see is actually water vapor which condenses locally around the cone's surface due to the pressure differential. Normally, you can't see the shock wave with the naked eye, but in those movies the local humidity is high enough so that the condensation make the shock wave visible.
Interestingly, you can sort of tell how fast the plane is moving by the "steepness" of this cone. If the cone is "flat" (i.e. almost vertical), the plane has just passed Mach 1. If the cone is "steeper" (e.g like a 45 degree angle), the plane is going much faster than Mach 1. The "steepness" of the cone is proportional to the plane's speed. I can probably dig up the exact formulas from an old Gas Dynamics text if any one is curious.
Back on topic. I wish they made some Ace Combat games for the Xbox. I can't believe the Xbox doesn't have any Jet sims (well, it has one but the reviews said it blew).
Edit: spelling
