BLOG: Weather played role in 'loud blast' in Gaston Co. neighborhood

BLOG: Weather played role in 'loud blast' in Gaston Co. neighborhood


50 pounds of Tannerite was shot using a high-powered rifle at Miles Road/Loray Farm Road just before 7 p.m. Sunday. This was an effort by some property owners to break up beaver dams in the area, so I am told by eyewitnesses.

Actually, this is not all that uncommon, as it seems we hear about this in east Gaston quite a bit. The weather conditions played a big role in allowing for this "boom" to be heard over a huge area - from Shelby to Lincolnton to Denver and West Mecklenburg. We're in a pattern when the evenings/nights bring about a temperature inversion. This happens when damp, cooler and denser air is trapped near the ground, and warmer air is just up from the surface around 1 to 4,000 feet.

The warm air aloft - acting as a warm front of sorts - actually helped produce the rain we received early this morning...and after today's 60s, afternoon readings in the 70s with dominate!

Anyway, the inversion brings about another effect that makes the blast newsworthy: atmospheric ducting. Atmosphere ducting causes sound waves to travel over very long distances. This also happens when we get elevated thunderstorms like we did in South Charlotte earlier this month.

The thunder can sound extremely loud and travel a great distance because the sound waves bounce up and down between the ground and the inversion layer and travel across the landscape instead of dissipating up into the air. We didn't have thunder last evening, but the Tannerite explosions near the ground covered a huge area because of the atmospheric set-up described above.

For those who may not know, Tannerite is the brand name of a patented exploding target used for firearms practice, sold in kit form and containing the components of a binary explosive.

The explosive comprises a combination of ammonium nitrate and/or ammonium perchlorate (oxidizers), and a fuel — primarily aluminum powder — that is supplied as two separate powders that are mixed by the user. The combination is relatively stable when subjected to forces less severe than a high-velocity bullet impact, such as a hammer blow, being dropped, or impact from a low-velocity bullet or shotgun blast. It is also not flammable — an explosion cannot be created by a burning fuse or electricity.

Because it is sold as two separate powders, it can be transported and sold in many places - including Gaston County - without the legal restrictions that would otherwise apply to explosives. The target system as a whole is the patented, trademarked product called Tannerite, although the term is often used to refer to the explosive mixture itself, and other combination explosives are often generically referred to as Tannerite.

- Meteorologist Al Conklin