BRIDGEPORT, W.Va. (WBOY) — With summer in West Virginia comes lightning storms.
The gigantic sparks of electricity can make for some elaborate and beautiful free light shows, and while no two bolts look identical, lighting can actually be broken up into different distinct types based on the type of charge and where the bolts go.
But first: What has to happen to create lightning?
According to the NOAA National Severe Storms Laboratory (NSSL), air acts as an insulator between positive and negative charges inside a cloud that is a part of a storm, and/or between that cloud and the ground. As the charges build up, the air’s insulating capacity breaks down, resulting in a quick discharge of electricity, temporarily equalizing the charged regions in the atmosphere, until it builds up again and the next bolt is discharged.
The bolt can go to a few different places, but according to the NSSL, the most common type is cloud-to-ground (CG) lightning.
Of CG lightning, most bolts are negatively charged. The negatively charged channel that shoots out of the cloud isn’t visible to the human eye until it nears the ground, but it attracts positively charged streamer channels, which the NSSL says usually come from taller objects in the area like trees and telephone poles, to reach upward. When the positive and negative charges connect, the electrical current that’s visible to the human eye, called a return stroke current, is created. A negative CG flash can consist of up to 20 return strokes according to the NSSL.
Storms with CG lightning may not always look the same though. There are less common positive CG strokes, where the downward traveling channel from the cloud is positively charged instead of negatively charged. The NSSL said those charges are more likely to only have one return stroke, rather than several.
These storms can also be more dangerous according to the NSSL, because their peak electric current is often stronger than that of negatively-charged storms and their flash duration is often longer. The NSSL says that longer duration has made some believe positively-charged storms are more likely to cause fires.
Spider lightning, which is long, horizontally traveling flashes that are usually on the bottom of stratiform clouds is more often linked to positive CG flashes, according to the NSSL.
According to the NSSL, it is possible for ground-to-cloud lightning to travel upward into a storm cloud is possible, but this is very rarely self-triggered. It usually originates from very tall structures like rockets and towers and travels upward into the cloud, but on rare occasions can be “self-triggered.” This usually happens during winter storms with strong winds according to the NSSL.
Cloud-to-air or CA flashes do have visible channels that extend out into the air around the storm but do not actually strike the ground
Some great examples include June 16th’s lightning storms visible in north central West Virginia.
In this type of lightning, the flashes do not reach the ground, instead remaining within the storm cloud, jumping between different charge regions. Clouds light up in flashes during this type of lightning, though other types of lightning usually accompany it.
When intra-cloud flashes are embedded within a cloud that lights up as a sheet, it’s called sheet lightning.
The term “heat lightning” describes any lightning of any type that is too far away for the thunder to be heard.