Why does a cloud form around a plane/jet when it breaks the sound barrier?

Question

I watched a video of this on youtube, and I found myself wondering why this happens! I suppose it's some sort of accumulation of the water molecules or being pulled or something... but what exactly is it? I will pick a best answer today! THANKS!!!!!!!!!!!

Answer 1

It doesn't always, in fact it's comparatively rare. The conditions have to be right, i.e. humidity, temperature, etc...

The shock wave from a supersonic aircraft is known as an "N" wave. In other words, there is a region of compression at the nose of the plane, and a region of expansion around the middle and tail.
http://www.dfrc.nasa.gov/gallery/photo/Schlieren/Small/EC94-42528-1.jpg
http://images.military.com/pics/BA_Sonic_Boom_opt.jpg

The leading edge of the shock wave compresses and heats the incoming air, causing some of it's heat energy to radiate away. The trailing portion of the wave rapidly expands and cools the air; if conditions are right, and the air is cooled sufficiently, cloud droplets will form momentarily, before evaporating again, as the air is returned to it's normal state......

Technically, this is known as "Prandtl-Glauert Condensation."

(I'm, like, on an answers binge today, and I feel like I have to explain everything......)

~W.O.M.B.A.T.

Answer 2

Engineers used to believe you couldn't break the sound barrier because the air simply could not get out of the way (that's why they referred to the sound barrier as the "brick wall in the sky"). What happens is a volume of air around the aircraft is literally "forced" away from the aircraft as it exceeds the speed of sound. It's kind of like an implosion where a bunch of air molecules get more and more concentrated until they hit a point of critical mass and the end result is a rather violent explosion.

Answer 3

Shock wave creates areas of high pressure which condense moisture in the air forming a cloud.

Answer 4

temperature or pressure affect condensation, the 1st poster is correct.