Photo of Curtiss AT-9
Sunday, November 30th, 2008
Curtiss AT-9 was uploaded by Mr. Physics and was photographed at the Air Force Museum at Wright Patterson Air Force Base in Dayton, Ohio.

Curtiss AT-9 was uploaded by Mr. Physics and was photographed at the Air Force Museum at Wright Patterson Air Force Base in Dayton, Ohio.

Airbus A380 Superjumbo taking off at Vancouver International Airport. Airbus A380 Superjumbo at YVR was uploaded by dan.barnes.

Click to the photo to read up on this. Very interesting.
What happens visually though is still debated. It seems from the picture above that an unusual cloud forms. One theory is that a drop in air pressure at the plane causes water vapor to condense and form the cloud.
Seeing a Sonic Boom - How often? was uploaded by edhiker.