Topic: Ratio of Intracloud or cloud-to cloud vs. cloud to ground strikes

[DaleReid]

As the folks in Blitzortung forum subsection know, there are a lot of thunderous flashes that don't show up on the detectors, partly due to not enough stations sensing the stroke to validate it, but also only cloud to ground get counted I guess.

Which got me wondering.  It seems that a lot of intracloud strokes happen while watching a storm, and fewer cloud to ground.

Is there a rough ratio, or is it extremely variable?  I've watched some smaller cells drift by with constant flashing in the cloud, while no detectable ground strokes occur.

[corwyyn]

For me it seems to be highly variable with no good way to predict what type is going ot dominate in a storm.  Just in this current monsoon cycle down here in the Phoenix area I've seen a couple of storms come thru with what appeared to be a similar set of conditions to start off with, one produced a lot of C-G strikes while the other was mostly C-C.  The storm with the C-G strikes did seem to give us a bit more rain than the other but I don't know if that would have an effect on what type of lightning was produced.

[ocala]

Just going by the the storms I watch here in Florida it seems that instability in the atmosphere might have something to do with it. When the atmosphere is juiced  and you get  full sun before the storms  it seems the CG strikes are much more prevalent. When we have cloudy skies and less instability the storms produce more CC lightning.
Overall though, just guessing here, I think there are more CG strikes. At least in my area.

[miraculon]

Wikipedia sayeth:

Intra-cloud lightning is the most frequently occurring type.

Their footnoted reference from NASA [42] http://thunder.nsstc.nasa.gov/primer/primer2.html says that it also depends on the particular storm. From my experience this seems to be true. I have seen storms with vivid CG lightning, yet others with just that "rumble of thunder" that is cloud-cloud.

Types of Lightning Discharges

THE MOST COMMON TYPES OF LIGHTNING
LightningCloud-to-ground lightning is the most damaging and dangerous form of lightning. Although not the most common type, it is the one which is best understood. Most flashes originate near the lower-negative charge center and deliver negative charge to Earth. However, an appreciable minority of flashes carry positive charge to Earth. These positive flashes often occur during the dissipating stage of a thunderstorm's life. Positive flashes are also more common as a percentage of total ground strikes during the winter months.

Intra-cloud lightning is the most common type of discharge. Intra_cloud Lightning 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.

Greg H.

[Cutty Sark Sailor]

10-25% is C-G or G-C