Fireworks

We've seen a few of these ubiquitous Lowe's superstores in the news this spring, destroyed by tornadoes. . . so why not feature an image of fireworks above this monstrosity of a symbol to unrestrained capitalism. These images were made last week but they kind of look like holiday fireworks to me. This week we're back to brutally sunny, dry, hot weather across the Florida peninsula.



One often hears comments about Central Florida being the "lightning capital of the world." That's something someone made up and spread over the internet. The statement is not based on scientific evidence. Central Africa receives many more lightning strikes per mile, per year than we do. Perhaps the lightning strikes over Florida are just a bit more visible here in the land of tourists, beaches theme parks, and mega-malls.

According to NASA's Global Hydrology and Climate Center (GHCC) Intra-cloud lightning is the most common type of discharge (pictured above as a thunderstorm died last week over a nearly empty Lowe's Store parking lot). This occurs between oppositely charged centers within the same cloud. Usually the process takes place within the cloud and looks from the outside of the cloud like a diffuse brightening which flickers. However, the flash may exit the boundary of the cloud and a bright channel, similar to a cloud-to-ground flash, can be visible for many miles.

The ratio of cloud-to-ground and intra-cloud lightning can vary significantly from storm to storm. Storms with the greatest vertical development may produce intra-cloud lightning almost exclusively. Some suggest that the variations are latitude-dependent, with a greater percentage of cloud-to-ground strikes occurring at higher latitudes. Others suggest that cloud-top height is a more important variable than latitude.

Details of why a discharge stays within a cloud or comes to ground are not understood. Perhaps a flash propagates toward the Earth when the electric field gradient in the lower regions of the cloud is stronger in the downward direction.

Depending upon cloud height above ground and changes in electric field strength between cloud and Earth, the discharge stays within the cloud or makes direct contact with the Earth. If the field strength is highest in the lower regions of the cloud a downward flash may occur from cloud to Earth.

Inter-cloud lightning, as the name implies, occurs between charge centers in two different clouds with the discharge bridging a gap of clear air between them.