The recent bout of cold weather and a wave of training exercises have contributed to an upswing in sonic booms, according to officials from nearby air force bases.

The noises frequently occur during routine aircraft testing at sites like Edwards Air Force Base, 50 miles west of Barstow.

When colder weather hits, sonic booms can travel well beyond their normal 70 to 100 mile range, especially during the months from November to April, according to John Haire, director of operations and media relations chief at the base.

The sound travels better when temperatures drop, said Haire, adding that cloud cover also causes the sonic booms to reflect off both the ground and the cloud ceiling, bouncing the sound waves farther.

"It insulates it," he said.

A sonic boom occurs when an aircraft travels near the speed of sound, creating lots of compressed air in front of the aircraft and a vacuum trailing behind, Haire explained.

When the compressed air, which has built up enormous pressure, escapes into the vacuum, a boom can reverberate for over a hundred miles.

Another way to see it, said Haire, is to think of a balloon. When a balloon is popped, the contained air goes from being under great pressure to being released so rapidly that it makes a "pop" sound, said Haire, similarly to a sonic boom.

A series of aircraft training, called red flag exercises, at Nellis Air Force Base near Las Vegas has likely added to the occasional booms, said Public Affairs Officer Cpt. Amanda Ferrell.

According to Ferrell, aircrafts including fighter planes, bombers, and helicopters from bases across the United States and as far away as Great Britain convene at the base for two-week training sessions. The most recent session concluded Feb. 6, and focused on training the pilots for overseas combat scenarios, said Ferrell.

Ferrell said that residents with concerns can contact the base, and situations that seem out of the ordinary will be investigated.

Haire noted that Edwards and Nellis are two of seven military installations in the region that regularly test aircrafts that may be producing the sonic booms.