Positive vs. negative cloud-to-ground discharges

Cloud-to-ground discharges are classified according to the polarity of the transferred charge. Negative CG (transferring negative charge to the ground) are by far the most common and make up the majority of all discharges. Positive CG are rarer, but often transfer a much larger charge and release more energy Boccippio 1995.

For the Schumann resonance, positive CG discharges are exceptionally significant: thanks to their large charge moment they radiate particularly strongly in the ELF band. They tend to be associated with the most intense transient phenomena in the SR signal — the so-called Q-bursts — as well as with sprites, one type of phenomenon above storms (transient luminous events) Boccippio 1995.

While the continuous "background" of the SR arises from the superposition of ordinary, predominantly negative discharges, exceptionally strong positive discharges appear in the record as isolated, energy-charged spikes. Transient Q-bursts are treated in more detail in cluster I.