Features of lightning around Japan over a four-year period are described using World Wide Lightning Location Network data based on global observations of very low frequency radio waves. Lightning density over land is lower than that over the ocean and the oceanic area of high density runs along the Kuroshio Current. The zone of highest density is found to the west of the Nansei Islands; however, very strong lightning rarely occurs there. Conversely, lightning density decreases gradually towards

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... the eastern part of the Kuroshio Current, where the occurrence of very strong lightning increases. The ratio of very strong lightning in most of the analysis area tends to increase in the cold season, and it becomes large in areas where lightning frequency is low. Furthermore, both very weak and strong lightning have a tendency to occur in areas where rain intensity is not strong.