Here's this image on postage stamps.
U.S. Air Force Academy graduates throw their hats in the air as the Thunderbirds fly overhead signaling the end of the Air Force Academy graduation ceremony, Colorado Springs, Colo., May 30, 2007. Defense Dept. photo by Cherie A. Thurlby (released)
The Thunderbirds are the Air Demonstration Squadron of the U.S. Air Force, based at Nellis AFB in Las Vegas, Nevada. The squadron tours the United States and much of the world, performing aerobatic formation and solo flying in specially-marked USAF jet aircraft.