The physics of thundercloud and lightning discharge. Comment on the note by Earle Williams and Sharon Stanfill The physical origin of the land–ocean contrast in lightning activity

Abstract

The arguments and conclusions of the commented Williams and Stanfill article in relation to the validity of the thermal and aerosol hypotheses advanced in order to explain the land-ocean contrast in lightning activity are critically re-examined. This reexamination reveals that the analysis presented by these authors is incomplete, thus weakening the corresponding conclusions.

Reply to the comment on “The physical origin of the land–ocean contrast in lightning activity”

“…If the island area-elevation relationship follows a power law, one does not expect to find a surplus of island elevations greater than 1000 m for areas smaller than 600 km 2 . In a later study, Williams et al [9], using different sets of islands and different measures of electrification, as suggested by PHM [3], found the same general transitional area.…”

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Pontikis et al [3] (hereafter PHM) have recently raised questions about the validity of analyses in Williams and Stanfill [5] (hereafter WS) that support the thermal hypothesis over the aerosol hypothesis as the primary explanation for the land-ocean contrast in lightning activity. A recent literature exchange on the same general issues has recently appeared [2,6], and an extension of the island analysis in WS [5] has also been completed [9].

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Lightning electrical characteristics during tropical summer thunderstorm in North-East India

“…Reports are available regarding the signatures from electric field pulses in particular thunderstorms (Sharma et al, 2005). The cloud-to-ground (CG) lightning flash characteristics and the effects of land-ocean contrast on lightning activity is also extensively studied (Gomes et al, 1998;Gomes and Cooray, 2004;Pontikis et al, 2004). The seasonal variation of globally measured ELF-VLF radio noise from lightning discharges has also been studied (Chrissan and Fraser-Smith, 1996).…”

Reply to ‘Comment on The physical origin of the land–ocean contrast in lightning activity’

“…In practice, the power law scaling is weaker than 1 2 (not shown), but still clearly evident. The main point is that if ATD or lightning activity is positively correlated with island area, then these parameters will also correlate positively with island elevation, as PHM [3] demonstrate.…”

“…Evidently, PHM [3] are of the view that the role of island elevation is the forced lifting of air "by large and mesoscale perturbations". In such a case, we would expect lightning activity to be induced in both daytime and nighttime, since these large-scale wave phenomena are not diurnally driven.…”