The speed of sound actually decreases, and then increases again as you go up in altitude. So when they say faster than the speed of sound, they mean the local s

The speed of sound actually decreases, and then increases again as you go up in altitude. So when they say faster than the speed of sound, they mean the local speed of sound (hence the sonic boom). This is explored (with graphs!) here for the case of Mr. Baumgartner's jump: http://blog.wolfram.com/2012/10/24/falling-faster-than-the-speed-of-sound/ http://blog.wolfram.com/2012/10/24/falling-faster-than-the-s...