Smog in South Mississippi

A smoggy day in South Mississippi prompted many residents to call local police and sheriff departments today trying to figure out what the smoke, haze and smell was in the area.

"We have a cap in the upper levels of the atmosphere from about 2,000 to 12,000 feet.  The cap acts as a lid and keeps anything from rising above that 2,000 foot mark.  The cap has caused smog in the area that could cause breathing problems for those with respiratory conditions.  The air will clear on Thursday behind the cold front," says Chief meteorologist Mike Reader.

Smog is a kind of air pollution with smoke and fog. It is sometimes caused by a cap in the atmosphere.

A cap is a layer of relatively warm air aloft (usually several thousand feet above the ground) which suppresses or delays the development of thunderstorms.

Air parcels rising into this layer become cooler than the surrounding air, which inhibits their ability to rise further. As such, the cap often prevents or delays thunderstorm development even in the presence of extreme instability.

However if the cap is removed or weakened, then explosive thunderstorm development can occur. See CIN and sounding.

The cap is an important ingredient in most severe thunderstorm episodes, as it serves to separate warm, moist air below and cooler, drier air above.

With the cap in place, air below it can continue to warm and/or moisten, thus increasing the amount of potential instability. Or, air above it can cool, which also increases potential instability. But without a cap, either process (warming/moistening at low levels or cooling aloft) results in a faster release of available instability.

Definition from